fifteenth episode of which series?
"Star Trek" episode
Joseph Pevney
Pevney also directed multiple episodes of noted television series, including "Bonanza", "", "The Paper Chase", and "Trapper John, M.D.". He tied with Marc Daniels for directing the largest number of original "Star Trek" episodes, including "The Devil in the Dark, "Arena", "The City on the Edge of Forever", "Amok Time", "Journey to Babel", and "The Trouble with Tribbles". "Star Trek" NBC executive Herb Solow and executive co-producer Robert Justman write, in their 1996 book "Star Trek The Real Story", of Pevney:
who was almost cast in star trek tos UNANSWERABLE the trouble with tribbles is it a film or series? It is the  fifteenth episode of the of the American science fiction television series "".
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Joseph Pevney [SEP] Biography
Beginning with "Shakedown" (1950), Pevney became a film and television director, with a directing career that spanned over 80 productions from 1950 to 1984. Among his films were "Female on the Beach" (1955) with Joan Crawford and Jeff Chandler, "Tammy and the Bachelor" (1957) with Debbie Reynolds and Leslie Nielsen, "Man of a Thousand Faces" (1957) with James Cagney as Lon Chaney, "The Crowded Sky" (1960), and Westerns such as "The Plunderers" (1960). Pevney also directed multiple episodes of noted television series, including "Bonanza", "", "The Paper Chase", and "Trapper John, M.D.". He tied with Marc Daniels for directing the largest number of original "Star Trek" episodes, including "The Devil in the Dark, "Arena", "The City on the Edge of Forever", "Amok Time", "Journey to Babel", and "The Trouble with Tribbles".