(written from a Production point of view)
Kenneth Lavelle "K.L." Smith (26 October 1922 – 24 August 1981; age 58) was the actor who played the Klingon captain in the Star Trek: The Original Series third season episode "Elaan of Troyius". He filmed his scenes on Friday 31 May 1968 at Desilu Stage 9.
Smith made guest appearances on numerous television series, including Gunsmoke, Rawhide, The Untouchables, Wagon Train, Bonanza, The Virginian, and Gene Roddenberry's The Lieutenant (starring Gary Lockwood).
He and fellow Star Trek actors Leonard Nimoy, Lawrence Dobkin, and William Schallert had uncredited appearances in the classic science fiction film Them!. Smith's other feature film credits include The Wild One (1953), Pushover (1954), Oh… Rosalinda! (1955, with Jill Ireland), and the Elvis Presley movies Jailhouse Rock (1957, with Dick Dial) and Roustabout (1964, with Lance LeGault, Marianna Hill, Terri Garr, and Carey Foster).