(written from a Production point of view)
Peter Paul Fix (13 March 1901 – 14 October 1983; age 82), was an American actor born in Dobbs Ferry, New York. He appeared in the Star Trek: The Original Series first season episode "Where No Man Has Gone Before" as Doctor Mark Piper. He filmed his scenes between Monday 19 July 1965 and Tuesday 27 July 1965 at Desilu Culver Stage 15 and Stage 17.
Fix is one of only two Star Trek actors verified as a veteran of the First World War (the other being Ian Wolfe), where he served in the US Navy. His birth of 13th of March, 1901 makes him the earliest born actor born in the 20th century.
Following the Navy, Fix became an incredibly busy character actor who got his start in local productions around his New York home. By the 1920's he had moved to Hollywood and performed in the first of almost 350 movie and television appearances. In the 1930's, he became friends with John Wayne, coaching him in acting, and eventually appearing in about twenty-five of his films. Many of his early characters were scoundrels of one sort or the other; as he matured, he took on more benevolent, avuncular roles (such as Doctor Piper). He is most well known as Micah Torrence from the ABC series The Rifleman, appearing for the show's entire run. Bill Quinn, who played the father of Piper's successor, Doctor Leonard McCoy, in the fifth Trek film was a semi-regular on that series. One Rifleman episode, entitled "Three Legged Terror", featured not only Fix and Quinn, but also John Hoyt, the man who played Piper's predecessor, Doctor Phil Boyce, in the first Trek pilot.
Other television credits included The Adventures of Superman (1953-1954, with Anthony Caruso, Joseph Mell, and Elisha Cook, Jr.), recurring appearances as District Attorney Hale on Perry Mason (1957-1963), The Twilight Zone (1964), The F.B.I. (1965-1973, with Marj Dusay, Clint Howard, Steve Ihnat, Paul Carr and series regular Stephen Brooks), The Time Tunnel (1966, with James Darren, Whit Bissell, Lee Meriwether and Paul Carr), Voyage to the Bottom of the Sea (1966), The Wild Wild West (1966-1967, with Sarah Marshall, Michael Dunn and Anthony Caruso), Owen Marshall: Counselor at Law (1971, with DeForest Kelley) and Mannix (1972, with Rex Holman and Byron Morrow). He appeared in the Battlestar Galactica episode "Take the Celestra" as Commander Kronus (1979).
On film, Fix was as prolific and movie credits he accumulated included among others the 1955 war movie The Sea Chase, which was served by Art Director Franz Bachelin, the only known other Star Trek affiliated World War I veteran, whereas he was cast as Judge Taylor in the 1962 classic legal drama To Kill a Mockingbird, co-starring Charles Dierkop, Richard Hale, John Megna, Frank Overton, Brock Peters and William Windom. In 1970 he had a smaller role in Michelangelo Antonioni's counter-culture film, Zabriskie Point, which also featured Lee Duncan. He appeared again with DeForest Kelley in the movie Night of the Lepus (1972).
Fix died in Los Angeles, California, as a result of kidney failure.
Samuel A. Peeples, the writer of "Where No Man Has Gone Before", thought very highly of Paul Fix. In a 1988 interview, Peeples commented, "I knew Paul for many years, and he appeared in some of the shows I did [....] In my opinion […] [he was] a splendid actor." (The Star Trek Interview Book, p. 118)