"Skin of Evil" is the 23rd episode of the first season of the 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.The series follows the adventures of the crew of the Starfleet starship Enterprise-D.