American actor turned director (1921–1998) who directed The Enemy Within, the first-season original Star Trek episode in which a transporter fault splits Captain Kirk into two halves.
Leo Penn began as an actor before becoming a prolific television director, with credits running from the 1960s to the 1990s on dramas, westerns and detective series.
His single Star Trek credit is The Enemy Within, written by Richard Matheson and made early in the first season. A transporter malfunction divides Kirk into a gentle, indecisive captain and a savage double, while Sulu and a landing party slowly freeze on the planet below. The episode gave William Shatner a showcase dual role and is remembered for the first use of the Vulcan nerve pinch, which Leonard Nimoy suggested during filming.
Penn did not direct for the series again, though he remained in steady demand elsewhere in television for three decades.