Khandu, The actor in the pilot was Jeffrey Hunter, who was much bigger than Shatner at the time. One reason he possibly didn't make it "big" is because he died in 1969.

Cast as Christopher Pike, captain of the U.S.S. Enterprise, in the original "Star Trek" pilot in 1964, but turned down option to continue the role in series. Pilot was later incorporated into a two-part episode in Star Trek's first season.

This quote comes from this page. (This page also say that he apparently wanted the role of the father in The Brady Bunch. He wasn't given the role, and died before the program premiered).

An amusing quote from Hunter: "I was told I had arrived when, during the shooting of "The Searchers", they gave me almost as much ammunition as they gave John Wayne.

I didn't ever watch Shatner's cop show, but I did like some of his earlier work. And I really liked him on Twilight Zone as the air passenger who looks out the window to see it shredded by something on the wing.

SRS