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, and originally aired on April 25, 1988, in broadcast syndication. The story premise was written by Joseph Stefano, and the screenplay 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, which is being held captive by an alien life form called Armus (Mart McChesney, voiced by Ron Gans). In investigating the crash, Lieutenant Tasha Yar (Denise Crosby) is killed by Armus, and Troi is eventually rescued after Captain Picard (Patrick Stewart) distracts the alien.

Yar's death in the episode was the result of Crosby asking to be released from her contract, although her last filmed episode was "Symbiosis". The manner of her 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, especially the manner of Yar's death and the Armus creature in general.