I’d heard from somewhere that Tainted Love by Soft Cell was actually a cover by someone else. I decided to look for myself. Turns out the original was done by Gloria Jones in 1964, and has spawned a lot of covers. How many? [http://www.coversproject.com/artist/Gloria+Jones]This]( [url) many. Quite enough to fill a CD, I believe. And by gum, I’m gonna try to do it.
Any other massively covered songs? What’s the record, so to speak?
Well, I don’t know about an entire CD, but Spirit in the Sky* has at least enough covers for a respectable side of an old 33 1/3 RPM vinyl disc.
All the covers of Black Sabbath songs would fill up several dozen CDs, with some songs filling an entire CD alone. Lessee if I can C&P them all:
“Black Sabbath” – Acheron, Dirty Lust, Hand of Doom, Iced Earth, Mudslinger, Sort Sol, Type O Negative, Anthrax.
“The Wizard” – Botch, Bullring Brummies, Rondellus, Scorn.
“Behind the Wall of Sleep” – The Macabre, Rondellus, Static-X.
“N.I.B.” – Anacrusis, Blood Coven, Cave-In, Dirty Lust, Opium Jukebox, Pitch Shifter, Premoniction, Primus, Ugly Kid Joe, White Stains.
“Evil Woman” – All Steel Coaches (not an original Sabbath song)
“Wicked World” – Spirit Caravan.
“Warning” – Eric Jerardi Band (not an original Sabbath song)
“War Pigs” – Bathory, Dream Theater, Faith No More, Hand of Doom, Loudness/Sly, Magdalen, Opium Jukebox, Rondellus, Sacred Reich, Sheavy, Vital Remains, Webstrarna.
“Paranoid” – The Clay People, Debauchary, Dirty Lust, Hand of Doom, The Lounge Brigade, Megadeth, Opium Jukebox, Oven & Stove, Ruder Than You, Skrewdriver, “A String Quartet Tribute to Black Sabbath”, Type O Negative, Ultraviolence.
…and so on…
My dad quite literally filled a CD with Ring of Fire covers once. I think he had about 16 of them.
I also once read that Pressure Drop by Toots & the Maytals is the most covered ska song, but I’ve only heard the Specials cover it.
I remember Casey Kasem saying years ago that “Yesterday” was the most covered song.
You could probably make a box set of “My Generation” covers.
I remember reading that “Yesterday” had some obscene amount of covers… don’t quote me though 
Why not? It does. Yesterday is the most covered song of all time; according to the Guinness Book of Records, it’s been covered more than three thousand times - one hell of a box set.
Second place goes to the Kingsmen’s “Louie Louie”, with 1600 straight covers plus a rather large number of songs that stole the main riff. Rhino Records have already released The Best of Louie Louie Vols. 1 and 2 - check Amazon for details.
Knockin’ on Heaven’s Door has been covered enough times for an EP just from artists I can name - Clapton, The Fall, Warren Zevon, Guns ‘N’ Roses, and at least two disaster tribute versions.
Thea - a single live bootleg of Doctor and the Medics performing Spirit In The Sky would be enough to fill an album. They always finish their shows with it, and it’s been known to go on for over an hour.
Let’s not forget “Memory” from CATS. I have a CDR of different foreign language (non-English) covers of the song.
A slew of songs from musicals would qualify.
A local radio station was between formats, and for a few days they claimed to be the “all Louie Louie station”, and played nothing but “Louie Louie” covers (from Rhino albums, I’d bet).
In my collection -
Gloomy Sunday - 17 covers
My Funny Valentine - 16 (probably hundreds more, it is a standard after all)
Wayfaring Stanger - 15 covers
People here in Oz fondly remember “Stariways to Heaven”, twenty or so covers of the Led Zep classic, performed in various styles. The Rolf Harris version was apparently a hit in England.
According to the Covers Project site, “Wish You Were Here” has about 15 covers. They appear to be missing Radiohead’s cover in their list, which would put it at 16. You could make a pretty respectable cd out of that.
I’m starting to doubt the Covers Project, anyway. It said TaTu did a cover of Frank Zappa’s Dirty Love, which I couldn’t find any other reference of (and the hits you get with the search “tatu dirty love”…). It also said Frank Zappa did a cover of DEVO’s Mongoloid, which I was again not able to verify.
I’m going to try for the Tainted Love CD.
I don’t know how many covers have been released of Little Wing and Born under a Bad Sign, but it seems like bar bands do love to play those songs. (Not that I’m complaining.) I’ll bet you could make a CD out of those.
I have a CD that is all covers of John Hiatt songs. Love it!
I remember an interview with Cab Calloway where he claimed to have put out an album of versions of Minnie teh moocher in every diferent music style he could…blues, rock, country … the mind sort of boggles=)
not sure how true it is, it was back in the early 80s …
The most famous cover of that one that I can think of is by the Clash.
All Along the Watch Tower is done by quite a few people these days.
DMB
Howie Day
Lenny Kravitz
Phish
Dylan (or was it a Dylan song done by Hendricks)
My Self… 
My wife would like to remind you not to forget the U2 version, off of Rattle and Hum.
Songs by people like George Gershwin, Cole Porter, Jerome Kern, Harry Warren, etc. have hundreds of covers. It ridiculously simply to come up with a boxed set’s worth of several of their songs.
The same with a lot of blues songs.
In the rock era, don’t overlook Dave Mason’s “Feelin’ Alright?” At one point in the late 60s, it was being covered every three weeks.