Leonard Nimoy as Spock in the original Star Trek series
(1966-1969).

In April 2010, Leonard Nimoy announced his retirement from
playing the Star Trek character Spock. His retirement has not
included voice acting.

William Alan Shatner gained worldwide fame and became a cultural icon for
his portrayal of James T. Kirk, captain of the USS Enterprise, in the science
fiction television series Star Trek on NBC from 1966 to 1969.

William Shatner as Capt. Kirk

Leonard Nimoy (L) as Hansen on the Twilight Zone episode "A Quality of
Mercy" (December 29, 1961)

Tales of Tomorrow is an anthology science fiction series that was performed
and broadcast live on ABC, Friday’s from August 3, 1951 to June 12, 1953. It
featured such stories as Frankenstein, starring Lon Chaney, Jr., and 20,000 
Leagues Under the Sea with Thomas Mitchell as Captain Nemo. Other
episodes featured such performers as Boris Karloff, Brian Keith, Rod
Steiger, Leslie Nielsen and Paul Newman. The series had many
similarities to the later Twilight Zone. Tales of Tomorrow ran for
a total of eighty-five 30-minute episodes.

A 27-year-old Paul Newman received his very first screen credit when he played
a young Army sergeant in the episode "Ice From Space," originally broadcast on
August 8th, 1952.
 

“Space Seed” is a first-season episode (#24) of Star Trek: The Original Series,
that was first broadcast on Thursday, February 16, 1967. It introduced the popular
villain Khan Noonien Singh, played Ricardo Montalbán. The 1982 film Star Trek ll:
The Wrath of Khan serves as a sequel to this episode.