Skin of Evil

"Skin of Evil" is the 23rd episode of the first season of the American science fiction television series Star Trek: The Next Generation; it first aired on April 25, 1988, in broadcast syndication. The story premise was written by Joseph Stefano, whose teleplay was re-written by Hannah Louise Shearer. The episode was directed by Joseph L. Scanlan.

Set in the 24th century, the series follows the adventures of the Starfleet crew of the Federation starship Enterprise-D. In this episode, the Enterprise races to rescue Deanna Troi (Marina Sirtis) from a crashed shuttle, who is being held captive by Armus, an alien life-form (Mart McChesney, voiced by Ron Gans). In investigating the crash, Lieutenant Tasha Yar (Denise Crosby) is killed by Armus; Troi is eventually rescued after Captain Picard (Patrick Stewart) distracts the alien.

Yar's death in the episode was the result of Crosby's request to be released from her contract. (Episodes were filmed out of order; the last first-season Yar episode filmed was "Symbiosis", which in first-run syndication immediately preceded "Skin of Evil".) The manner of Yar's death was intended to be typical of the threat posed to a security officer, and was what the show's creator Gene Roddenberry had intended. The episode was received poorly by most critics, who rejected in particular the Armus creature and the manner of Yar's death.