Rigor Mortis Sets In is the third solo album by John Entwistle, who was the bassist for The Who. Distributed by Track Records, the album was named John Entwistle's Rigor Mortis Sets In in the U.S. Co-produced by Entwistle and John Alcock, it consists of three classic Fifties rock and roll covers, a new version of the Entwistle song "My Wife" from The Who's classic album Who's Next, and new tracks (only six of the ten songs were new). Rigor Mortis Sets In set in motion John Entwistle assembling his own touring unit during the increasing periods of The Who's inactivity.
Bearing the dedication "In Loving Memory of Rock 'n' Roll 1950–∞: Never Really Passed Away Just Ran Out of Time", Entwistle's affection for Fifties rock and roll was evident by covers of "Mr. Bass Man", "Hound Dog", and "Lucille". As George Lucas had released American Graffiti at the same time as Rigor Mortis Sets In was released, creating a huge market for Fifties nostalgia, Entwistle's timing was uncannily prescient. In Entwistle's original material for the album, light whimsy prevailed over the darker (and more creative) vein of Smash Your Head Against the Wall and Whistle Rymes. The album was completed in less than three weeks, ultimately costing $10,000 in studio time and $4,000 on liquor bills.
The cover art of the gatefold LP features on one cover an outdoor photo of a grave, whose heart-shaped headstone is engraved with the dedication described above, while the grave's footstone is inscribed "V.S.O.P." (a grading acronym for cognac). The opposite cover features a wooden coffin bearing a brass plate engraved with the album's name. The UK (Track) LP used the coffin on the cover and the gravestone on the inner gatefold, while the U.S. (MCA) LP had the opposite arrangement. Compact disc releases have been fronted with Track's original coffin cover, with the gravestone cover proportionally preserved inside as part of the liner notes.
Rigor Mortis Sets In had a rough launch due to its title and cover art. BBC Radio refused to play the album and banned it, ironically in part due to the influence of DJ Jimmy Savile who had just suffered a death in his family. The album's U.S. debut was problematic for MCA Records (Track's new American distributor), who insisted on appending the artist's name to the title, out of concern that the album's sales would be weak without the Entwistle name in the title.
The album was rated by AllMusic as a "Nosedive" in his career compared to Smash Your Head Against the Wall and Whistle Rymes. His covers of "Hound Dog" and "Lucille" were known as "lifelessly performed that it sounds like the band is merely attempting to imitate Sha Na Na instead of sending up the original tunes themselves". The song that was known as the biggest offender in this respect was "Mr. Bass Man" which replaces the enthusiasm of Johnny Cymbal's original version with a self-consciously campy production built on cutesy vocals guaranteed to make listeners grind their teeth.