On what TV series was William Shatner a regular before "Star Trek" (NBC, 1966-69)?

William Shatner a regular on the TV series “For the People” (CBS, 1965) before appearing on “Star Trek” (NBC, 1966-69).

Shatner played Assistant District Attorney David Koster.

On what TV series did William Shatner and Leonard Nimoy work together before "Star Trek" (NBC, 1966-69)? William Shatner and Leonard Nimoy both appeared in a 1964…
What science-fiction TV series did Leonard Nimoy appear in before "Star Trek" (NBC, 1966-69)? Leonard Nimoy appeared in the science-fiction TV series Zombies of…
What were the first names of Scott, Chekov, and McCoy on "Star Trek" (NBC, 1966-69)? Their first names of Scott, Chekov, and McCoy on "Star…
Who played Spock's love interest Leila on the "Star Trek" (NBC, 1966-69) episode called "This Side of Paradise"? Jill Ireland played Spock's love interest Leila on the "Star…
During what years was Goldie Hawn a regular on "Rowan & Martin's Laugh-In" (NBC, 1968-73)? Goldie Hawn was a regular on "Rowan & Martin's Laugh-In"…
In what year did NBC begin regular television transmission to the American public? NBC began regular television transmission to the American public in…

On what TV series was William Shatner a regular before “Star Trek” (NBC, 1966-69)?