I've put together a list of all the guest appearances in the Dead's early shows. I don't know of a site that provides a listing like this, and it's likely that I've forgotten or left out some guests, so if anyone notices something missing, please speak up!
This list is mostly limited to electric Dead shows where someone outside the band added a musical contribution.
It doesn't include shows for which we have no tapes - for instance, various unrecorded Airplane/Dead jams that happened over the years.
It doesn't include the New Riders' sets - though I should at least mention the 3/18/73 New Riders show where Garcia, Weir, and Godchaux all joined in. It also doesn't include the 1970 acoustic sets in which John Dawson & David Nelson regularly sat in for some songs, though other acoustic guests are noted.
It doesn't include announcers - some of whom, in the early days, are quite entertaining in their own right.
It doesn't include studio sessions (for instance, the Jon Hendricks session in late '66). For a good discography and listings of various studio collaborations (including Garcia's non-Dead projects), check www.deaddisc.com.
It doesn't include the collaborations with David Crosby in late '70 (for instance, the PERRO sessions or the 12/15/70 Matrix show), which could be a whole separate discussion.
It doesn't include the many tapes of Garcia jamming with other musicians - for instance, Country Joe (the Fillmore West '69 "Donovan's Reef jam"), Jefferson Airplane (Family Dog 9/6/69), the Allman Brothers (Cow Palace 12/31/73), Doug Sahm (Austin 11/23/72), or various early jams with Airplane members and others.
But I did include a couple illuminating non-Dead shows that happen to be on the Archive, where Dead members have a strong presence, as well as the notorious Hartbeats shows since those have so much Dead material.
I've decided to skip the early '66 Acid Tests, since they're so full of audience mikes and Prankster chatter - the Dead themselves were the guests. So we'll start at the dawn of 1967:
12/1/66 Matrix - An unknown blues singer & harmonica player joins the Dead for Yonder's Wall and My Own Fault.
1/14/67 Great Human Be-In - During a speedy instrumental Schoolgirl, Charles Lloyd plays flute and does a jazzy, aggressive stream-of-consciousness rap.
6/18/67 Monterey Festival - This is the earliest version of Alligator we have - at the beginning of Alligator, someone's playing harmonica where the verses should be. It isn't Pigpen, since it's horrible and off-key (meanwhile he's probably singing into a dead mike) and later in Caution he plays harmonica in his usual style - but I had the impression it might be someone familiar with the song. (They also bleat a little bit in Cold Rain & Snow.)
7/23/67 Straight Theater - Garcia introduces Neal Cassady, who raps for a while while the Dead back him. For the first part they play an instrumental Lovelight (their first known version), then in the second part they get into a minimal 'space' - also the earliest space.
9/20/68 Berkeley - In this snippet of a show, the Dead abort a short Eleven to go into drums - they're joined by Shankar Ghosh and Vince Delgado (two percussionists from the Ali Akbar College of Music) for a 25-minute drum break, which ends the show with cries of "Ya, ya, yaketa!" Perhaps equipment or lysergic troubles prevented an Alligator jam - in any case, this must be the longest drum solo until 1978.
In October '68, after the temporary firing of Weir and Pigpen, a series of Mickey and the Hartbeats shows started at the Matrix - consisting of Garcia, Hart, sometimes Lesh, and any other musicians that might show up, jamming on a few Dead themes and some freeform explorations. Sometimes it's said that they were auditioning for new Dead members, but this is highly unlikely, since the other players were already in established bands. Garcia may have just wanted to open up a new side-project (we'd certainly see more of those in later years). It's less-known that Lesh isn't even playing during many of these shows - with the exception of 10/30/68, these are mostly Garcia/Casady duets. When Elvin Bishop shows up, the Hartbeats take a definite turn towards standard blues jams.
Not all the Hartbeats shows seem to survive - there are some undated fragments circulating - and occasional Hartbeats shows took place into '69, of which we only have the Aug 28 show with Howard Wales.
10/8/68 - Elvin Bishop & Jack Casady in the later sets.
10/10/68 - 'Marvin' (blues singer & harmonica player). I don't think Jack Casady was at the Matrix this night (he was playing with Hendrix at Winterland).
10/30/68 - Elvin Bishop; then Jack Casady in the second Dark Star.
12/16/68 - Garcia & Hart with Jack Casady, Spencer Dryden, David Getz.
12/24/68 - Garcia & Hart with Harvey Mandel, Elvin Bishop, Stephen Miller & John Chambers (not on the Archive).
1/24/69 - After Lovelight is cut off during this Avalon show, the drummers keep going, and someone onstage shouts into a microphone during the drums, clearly out of his mind at the end.
2/19/69 Fillmore West - Someone sings along with Pigpen in the second part of Lovelight. After Lovelight, the Dead stop the music
for twenty minutes of audience chanting and various guest speakers. For the second half of the
show, the Dead are joined by Gary Duncan on guitar.
Early '69 was a conspicuously guest-free time as the Dead played their limited setlist with Tom Constanten at show after show. As I've mentioned before, in April/May '69 a little setlist upheaval started as the Dead started bringing back bunches of old covers, adding more variety (and sloppiness) to their shows. All of a sudden in late spring, we see a whole torrent of guests taking the stage in Dead shows, which would continue through 1970.
4/4/69 - A mystery organ player guests in Lovelight, possibly Bob Powell of Sanpaku - clearly not Pigpen or TC, since he's not very familiar with the song.
5/11/69 - Santana percussionists Mike Carabello & Chepito Areas join the Dead in the Alligator drum section, and Garcia jams with the percussion; one of them sings a bit in Lovelight.
5/31/69 - Ken Babbs starts Baby Blue with a sad little rap; he's also heard rapping at length after Cold Rain & Snow.
6/6/69 - Jerry is late to the show (or too dosed to play), so Wayne Ceballos of Aum takes his place for almost the whole show, except for Lovelight. (He was previously misidentified as Elvin Bishop.) Needless to say, we get an extra dose of blues with Smokestack Lightning and Checkin' Up On My Baby. The Lovelight may be the longest ever, at 48 minutes (though some others come close).
6/7/69 - Janis Joplin sings with Pigpen in Lovelight in her usual blues-scat style. (This part of the show suffers from tape deterioration.)
6/8/69 - After an amazing first set, we get no less than two guests - Wayne Ceballos sings Lovelight instead of Pigpen (making it feel twice as long, though Pigpen seems to approve). Then Elvin Bishop (who played guitar in Lovelight) takes over again for a couple blues tunes with Pigpen, Things I Used To Do and Who's Lovin' You Tonight, before Garcia returns. There may possibly also an unknown keyboard guest in the set (though it could be Constanten), and Billy Nicks (Junior Walker & the All-Stars drummer) joins on percussion. All-Stars guitarist Philip Leno Wright also says Garcia brought him on for a solo at some point during this run, though I haven't found it.
6/13/69 - Wayne Ceballos sings Schoolgirl with Pigpen. (He was previously misidentified as Ronnie Hawkins.) Someone plays flute for a bit in the middle of Lovelight (most likely Gary Larkey, of Sanpaku), and Ceballos comes back for the raveup at the end.
6/14/69 - Wayne Ceballos sings in Lovelight again.
6/27-28/69 - A bunch of guests on these dates! On 6/27, Tom Ralston (drummer for the Cleanliness & Godliness Skiffle Band) sat in for Mickey Hart on drums for the first few songs. Peter Grant plays (barely audible) banjo in Slewfoot on 6/27, and more inaudible banjo in at least Mama Tried and Me & My Uncle on 6/28, and switches to pedal steel in Doin' That Rag (as on the album). John Dawson sings Me & My Uncle with Weir on 6/28. David Nelson plays a guitar solo in Mama Tried on 6/28.
7/7/69 - Deadlists suggests that Gregg Allman is playing organ in Lovelight. Not so - I only hear Constanten. (In any case, though the Dead didn't play with the Allmans here, there was a multi-player jam after the show, not recorded.) http://www.archive.org/details/gd69-07-07.sbd.clugston.3116.sbeok.shnf
7/12/69 - Madness breaks loose in Lovelight - Pigpen tries to get Mickey to sing, and Weir gives a mike to an enthusiastic audience member who starts shrieking and hollering the blues: "Let me tell you baby, you're a brown cow, let's go get stoned....."
8/2/69 - David Nelson plays guitar in Slewfoot and Mama Tried. He adds a different texture, and I wish he'd sat in more often!
8/3/69 - Very unusual (and anonymous) guests tonight - a fiddle player in Hi-Heel Sneakers, and then saxophone and fiddle in the Dark Star>Alligator>Other One>Caution jam. One of the most unique sets the Dead ever played, though the mix is poor. The guests have still not been identified - Charles Lloyd is presumed to be on sax, but the fiddle player is a mystery. David Nelson plays a guitar solo in Mama Tried again.
8/16/69 - Ken Babbs raps for quite a while after Mama Tried. Someone also raps about the "third coast" at the beginning of Lovelight; this used to be attributed to Babbs, but it is actually some mysterious stranger. A video of Dark Star also reveals a baby onstage with the band.
8/21/69 - Gary Larkey of Sanpaku plays flute in Minglewood Blues and China Cat. (He was previously misidentified as Charles Lloyd.)
8/23/69 - After Pigpen has the crowd yell "Howdy!" he asks for a volunteer: "Anyone wanna come up and testify? - anyone, come up and say something! Y'all chicken?" Some crazed fellow takes him up on it and starts screeching, "Woo-hoo! Everybody get it on! Have a good ol' time! Baby baby, do ya feel it?" and makes a little speech.....
(There are many more Lovelights in '70/71 where Pigpen would give the mike to delirious romantics in the audience. I don't have the heart to seek out any more examples, though.)
8/28/69 - Hartbeats with Howard Wales (Weir & Pigpen absent). There's also a flute player heard briefly in Dark Star.
9/7/69 - Not the Dead, but Garcia with some of the Jefferson Airplane playing some drunken garage-band oldies from their youth. A rare chance to hear Garcia singing Johnny B Goode (and the first known Big Railroad Blues) - but the playing's pretty rough.
9/11/69 - There's a stray audience tape with this date of an early Easy Wind which supposedly had a guest player on slide guitar; but this turned out to be from the 8/30/69 AUD, with Weir on slide.
10/25/69 - Stephen Stills plays guitar in Lovelight.
11/7/69 - After Mama Tried, someone in the audience plays the Star-Spangled Banner on a pennywhistle, to general hilarity - the Dead respond with a few little traditional ditties.
11/8/69 - In the Caution jam just before the Main Ten, someone recites a little poem in a Dylanesque manner - perhaps John Dawson. (Released on the Dick's Pick.)
12/10/69 - Stephen Stills plays guitar in Casey Jones, Schoolgirl, and Morning Dew, and sings Black Queen. (He probably played in Lovelight as well, but it cuts after two minutes.) Black Queen is excellent.
12/29/69 - Soon after the jam starts in Good Lovin', a disturbed audience member yells into a mike, and they stop for a bit while he's hustled off-stage. This isn't a "guest appearance", but it helps remind us that in many shows (as Garcia occasionally mentions) the stage must have been full of people wandering around - kids, dancers, freaks, and so on.....
1/23/70 - Around 12 minutes into Lovelight, someone screeches and hoots lamely with Pigpen for a couple minutes - Pigpen encourages him, "Anything you wanna say, go ahead, I'll follow ya." (This has been thought to be Joey Covington, I'm not sure why.)
2/1/70 - Peter Green plays guitar in Lovelight, and another Fleetwood Mac member hollers for a bit.
2/4/70 - Though it wasn't part of the Dead show, several bands were being filmed at the Family Dog this night; and at the end of the evening there was an "all-star jam" including Garcia, Santana, and the Jefferson Airplane guitarists, part of which was broadcast. It's not on the 2/4/70 Download Series CD, but it is on the "Night at the Family Dog" DVD.
2/11/70 - For the Dark Star>Spanish Jam>Lovelight, an enormous crew including most of Fleetwood Mac and the Allman Brothers joined the Dead onstage - Peter Green, Duane Allman, Mick Fleetwood, Danny Kirwan, Gregg Allman, Butch Trucks & Berry Oakley.
3/8/70 - A mystery guest takes the mike after Pigpen's Katie Mae and "sings" a blues while Pigpen and the band accompany him - then he continues shouting while someone else tunelessly bleats a harmonica all through Not Fade Away, while the Dead apparently ignore them. The singer was thought to be Wayne Ceballos, but is now said to be "Paul Michael Cantrell (aka Rathead)," a local high school student - Pigpen seems to have encouraged him onstage, for some reason. Hands-down the worst guest appearance. (The Archive link has a debate on whether this singer is Ceballos or not - which is ironic, since the genuine Ceballos on 6/8/69 is almost equally atrocious.)
"Wake Me, Shake Me" was a song done by the Blues Project. An audience member notes that "by the time the band did "Lovelight" there were maybe 50 members of the audience on stage with the band... The band members were surrounded by crazed audience members."
3/17/70 - This famed show, where the Dead played with the Buffalo Philharmonic Orchestra, doesn't survive on tape. But there are descriptions of the show here:
(As for lost shows, I should also mention 5/10/70, where the Dead jammed with the Allman Brothers again.)
4/9/70 - An unknown guest sings the improvised "Cowboy Song", an interesting Sugar Magnolia-type hoedown, as the audience stamp their feet.
4/15/70 - Deadlists says that during the Santana-like jam in the Other One, "A third guitarist sits in, and also someone on keyboards, and someone on congas." There is a mystery organ player, but there is no third guitarist.
6/7/70 - During the Other One drum solo, a lady gives a speech to the audience; not only that, but someone's singing off-mike during the Cryptical reprise. (Deadlists claims this is Robert Hunter.) Someone also sings "hey baby" over the opening of Cosmic Charlie. The Dead themselves, perhaps unsurprisingly, seem a little unfocused.
6/13/70 - According to Deadlists, "Dino Valenti and Gary Duncan appear on Good Lovin' and Lovelight." There may be a third guitar in Lovelight, but otherwise I can't hear them, so I'm skeptical of this. (Pigpen plays a neat piano in the New Speedway Boogie solo, though.)
7/14/70 - In the acoustic set, David Crosby plays 12-string on Cumberland Blues and New Speedway Boogie.
7/16/70 - At Bear's going-away party, Janis Joplin sings another Lovelight with Pigpen - this one is much raunchier than last year's.
7/70 - A KSAN broadcast from an unknown date of an in-studio "Bobby Ace" set - Weir on acoustic, Garcia on pedal steel, John Cipollina on slide guitar, Pete Sears on piano. Weir sings four acoustic songs. Known as "the Garage Tape;" not on the Archive.
8/19/70 - David Crosby plays guitar in Not Fade Away>Lovelight - unfortunately, in the audience tape it's hard to make him out.
9/17/70 - On Box of Rain, David Nelson plays guitar and Garcia plays piano, as on the album.
9/20/70 - In the acoustic set, David Grisman plays a second mandolin (along with David Nelson) for several songs. It's also notable that Garcia plays piano on To Lay Me Down, as he had on 9/19 (Pigpen usually played the piano during the acoustic sets).
11/11/70 - Jack Casady, Jorma Kaukonen, and Papa John Creach join the Dead during Goin' Down the Road and they play a series of fun jams, blues, and rockers to end the show.
11/16/70 - This Hell's Angels benefit has a few guests on several tunes - Steve Winwood on organ, Will Scarlet on harmonica, and perhaps Chris Wood doing some singing in Not Fade Away. (This show used to be known as 11/23/70, but 11/16 Fillmore has become the accepted date.)
An audience tape from this date also features Papa John Creach soloing on Good Lovin'. (Jorma and Jack may be playing too, though it's hard to hear.)
11/20/70 - The bonus set with Jorma Kaukonen and Jack Casady features quite a few hot jams and rockers, in better quality than 11/11.
11/21/70 - Only part of the set exists, a Cryptical>Other One medley. Ned Lagin played with the Dead (as photos show), but he wasn't plugged into the PA, so he's quite inaudible.
I should also mention here the 11/21/70 Boston radio show after this performance - Garcia & Weir play several acoustic songs and are joined by Duane Allman, who plays one acoustic instrumental. (This set is not on deadlists or the Archive.)
12/31/70 - During I Know You Rider, you can hear a woman screaming continually for quite a while; the Dead ignore her. After the song, another woman says into a mic, "Um, excuse me, I forgot my cape in the corner over there...." As Deadlists puts it, "Plainly things were a little out of control backstage; perhaps there was a mic live that shouldn't have been." (This is also the show where the Dead direct a spotlight onto an audience taper - Garcia shouts, "There's bootleggers among us - let's find out who these people are!")
12/31/70 - After the Dead show, in the wee morning hours Weir came back for an extra set with Hot Tuna (Jorma, Jack, Will Scarlet on harmonica, Joey Covington on drums) - playing a selection of oldies, most of them in the Dead's setlists, but here done Hot Tuna-style. This is a rare example of hearing Weir (rather than Garcia) as a guest.
From 1970-1972, Ned Lagin appeared at a number of Dead shows, playing organ during the jams - including 11/5/70, 11/8/70, 8/14-15/71, and 9/16/72. Sadly, he can scarcely be heard on any of the tapes, so I'll refer you to this indispensable site which lists his appearances:
He can be heard in these shows:
2/18/71 - Ned Lagin on clavichord in several songs, most notably the Dark Star medley.
4/7/71 - Ned Lagin is likely on piano, barely audible in the post-drums jam.
4/8/71 - Ned Lagin is faintly audible on electric piano, particularly in Dark Star.
Guest appearances dropped off significantly in 1971, as the Dead tightened up their shows. In fact, there were no others that year - except for three nights in the Fillmore East run in April:
4/26/71 - Duane Allman plays guitar in Sugar Magnolia, Hurts Me Too, & BIODTL. He's rather low in the mix on circulating tapes (and the song selection could be better). Apparently these songs were almost released on the Ladies & Gentlemen set, but were halted by legal issues. (One song has been released on the Skydog box set.)
4/27/71 - The Beach Boys emerge from the mists of time for a little mini-set in the middle of the Dead's set, playing a few of their own tunes with the Dead joining in for some '50s covers.
4/28/71 - In an even more surprising emergence, Tom Constanten reappears - not for a whole set, interestingly, but he plays in the Dark Star>St Stephen>Not Fade Away medley. This was released on Ladies & Gentlemen.
8/14/71 - Before the encore, David Crosby comes onstage and the band plays him Happy Birthday. (It's been claimed that he plays in Johnny B Goode & Uncle John's Band, but I don't think so.)
One summer jam session must be mentioned:
8/21/71 at Mickey Hart's barn - The Dead jam for a couple hours with John Cipollina, David Crosby, Ned Lagin, and Merl Saunders - and amazingly, it's taped. (An earlier "Day in the Country" jam at the Barn with a similar lineup was also recorded, but hasn't circulated.)
12/31/71 also has a raucous midnight start - during the opening Dancin' in the Streets jam, the radio announcer mentions that two men "took off their diapers and are running around the stage nude!" Someone (perhaps one of these men) shouts "Happy new year!" and some random shrieks into a mic during the jam. Afterwards, Weir announces that the stage is a mess....
1972-73 saw a few more guest appearances:
3/25/72 - Bo Diddley plays a set of his songs with the Dead as backing band during the Academy of Music run. Part of it was released on a Dick's Pick (along with the one-time-only Are You Lonely For Me Baby, How Sweet It Is, and Pigpen's last Smokestack Lightning, from the Dead's set) - and a horrible AUD tape is here:
7/16/72 - At the end of the show, Dickey Betts, Berry Oakley, and Jaimoe from the Allman Brothers join the Dead for a fantastic Not Fade Away>Goin' Down the Road>Hey Bo Diddley, and the Johnny B Goode encore. (I think Betts also appears on Sugar Magnolia, though he's barely in the mix.) Duane Allman unfortunately couldn't appear, since by this time he had merged with infinity. (By the way, the other two '72 Hey Bo Diddleys were done on 5/23/72 and 8/22/72, which are well worth checking out.)
9/10/72 - David Crosby appears in this excellent show, playing in Dark Star. (He's not very evident in the following songs.)
9/30/72 - Several witnesses in the reviews here report a topless dancer onstage - unfortunately, she doesn't appear on the tapes..... But judging by the Veneta '72 film, such sights were common among Dead audiences.
10/9/72 - Grace Slick appears, not topless but apparently drunk - to start the second set, she sings a Janis-style rap while the Dead play a blues jam. She returns to make a little speech about the band before Truckin'.
12/31/72 - David Crosby shows up again to play guitar in the fantastic Other One>Morning Dew jam.
6/10/73 - In one of their giant '73 shows, the Dead give us a famed third set with Dickey Betts, Merl Saunders & Butch Trucks. Interestingly, Garcia picks That's All Right and Takes a Lot to Laugh from his Keystone setlists.
7/28/73 - The encore is the highlight of the show - Not Fade Away, Mountain Jam, Around & Around, and Johnny B Goode with the Allmans and the Band. One of the only times (other than 12/31/73) where you hear Garcia actually playing in a Mountain Jam, rather than just quoting Donovan's melody. Garcia also appeared on some earlier Band encore songs, which circulate with the Band's set but not the Dead's: Have You Ever Been Mistreated, Da Di De Day, and Warm & Tender Love.
(A joint Dead/Allmans CD set was prepared some time ago from these '73 shows, but release has been delayed indefinitely.)
A new twist came in September '73. For eight shows in the 9/11 to 9/26 Northeast tour, Joe Ellis & Martin Fierro joined the Dead on horns for Let Me Sing Your Blues Away, the Weather Report Suite, Eyes of the World, Truckin' and Sugar Magnolia. These shows have aroused mixed feelings - while the horns added a free-jazz or New Orleans-ish tinge to the sets, some people feel they're more intrusive than enjoyable. It's also notable that the horns weren't added to other jam songs - and this tour in general was rather light on the deep jams. I suspect the horn players weren't given much practice time to work out arrangements - as a result, we get quite a few second-set jams of Truckin'>Eyes>Weather Report.
This is one show illustrating all the songs they played in: Let Me Sing Your Blues Away, Truckin', Eyes of the World, Weather Report Suite>Let It Grow, Stella Blue, and Sugar Magnolia.
Though not a Dead show, 11/28/73 is worth mentioning since Ned Lagin & Phil Lesh (unbilled) joined Garcia & Hart for a Seastones-inspired "Experiments in Quadrophonic Sound" concert - more prolonged and abstract than the usual Dead space-jam, but more listenable than Lesh & Lagin's 1974 adventures, since Garcia's doing some interesting things.
(This file has 11/28/73 divided into several AUD & SBD sections, which may not all be from that date, along with some non-Dead Constanten Tarot outtakes. A full AUD tape is also available, but not on the Archive.)
Starting on June 23, 1974, Ned Lagin & Phil Lesh played some Seastones pieces in-between Dead sets at most of the '74 shows. At the first show, Lagin also played in much of the second set, though I don't think he can be heard:
These bass drones & synthesizer noises are a bit too experimental for most people; but there were a few times in Europe and Winterland when the rest of the band would come out and turn Seastones into a full-band jam, leading into generally very spacy sets where Lagin could continue playing with the Dead:
9/11/74 Seastones>space>Eyes of the World>space>Wharf Rat
9/21/74 Seastones>Playin' in the Band
10/16/74 Seastones>space>Wharf Rat>space>Eyes of the World
10/16/74 Seastones>jam>Dark Star>Morning Dew (partly released on the Grateful Dead Movie Soundtrack, but with much of Seastones omitted)
Finally, there are a few 1975 guest appearances:
3/17/75 - Not a show but an unusual session at Weir's studio, in which David Crosby & Ned Lagin rehearse with the Dead on Lagin's birthday - mostly on a couple Crosby songs, Low Down Payment and Homeward Through the Haze. Not one of the more interesting '75 sessions for me (though others differ).
Lagin appears on a number of the early Blues for Allah studio sessions - the only other one I'll list here is 4/17/75, where Crosby, Lagin & possibly John Cipollina join the Dead, without Garcia or Godchaux, for some instrumental run-throughs. Cipollina is barely present, and it's a very repetitive session of rhythm takes:
3/23/75 - Ned Lagin (Fender Rhodes) & Merl Saunders (Hammond organ) join the Dead for this surprising Blues for Allah show. Not only is it a hardcore set to drop on an unsuspecting audience, it's unique in having three keyboardists. (It was released on the Beyond Description bonus CD.)
6/6/75 - Not a Dead show, but a Seastones show with Lagin, Lesh, Garcia, Hart, and David Crosby. (Not that anyone can be recognized in the barrage of electronic sound effects.)
https://archive.org/details/gd73-11-28.sbd-seastones.finney.968.sbefail.shnf (the last disc)
9/28/75 - Matt Kelly plays harmonica on Music Never Stopped and BIODTL.
Once the Dead started touring again, I don't recall any guests onstage until mid-'78, with the likes of Hamza el-Din, Lee Oskar, John Cippolina, and various Pranksters & motorcycles & banjo ladies....but that is a list for someone else to start.
Here is a list of the later years put together by Earl Powell from Deadbase, though it's not complete:
And here is a new compilation of all the guests at the Dead's shows over the years - there are some omissions, and the chronology skips around, but overall it's pretty comprehensive, over 80 hours long: