Rigor Mortis Sets In is the third solo studio album by the English rock musician John Entwistle, who was the bassist for the Who at that time.

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 (1971) and Whistle Rymes (1972).

BBC Radio refused to play the album and banned it, ironically in part due to the influence of disc jockey (DJ) Jimmy Savile who had just suffered a death in his family.

The album was considered by AllMusic to be a "nosedive" in Entwistle's career compared to Smash Your Head Against the Wall and Whistle Rymes.

Critic Donald A. Guarisco opined that the covers of "Hound Dog" and "Lucille" were "so lifelessly performed that it sounds like the band is merely attempting to imitate Sha Na Na instead of sending up the original tunes themselves", and noted the cover of Johnny Cymbal's "Mr. Bass Man" as having "a self-consciously campy production built on cutesy vocals guaranteed to make listeners grind their teeth".