Shempo was a hologram in Ensign Beckett Mariner's holoprogram Crisis Point: The Rise of Vindicta. He was a character who was supposed to be played by Ensign Brad Boimler, and was a henchman of Vindicta. She phasered him out of existence when he brought her coffee instead of tea. (LD: "Crisis Point")
Shempo was voiced by Ben Rodgers.
The name "Shempo" is a reference to Fake Shemp, a term coined by Sam Raimi for the Evil Dead movies, named after one of The Three Stooges. According to Bruce Campbell's memoirs, If Chins Could Kill: Confessions of a B Movie Actor, it refers to someone who appears in a film as a replacement for another actor.