This particular night, though, he was recovering from hip surgery and couldn't sleep, so he was watching TV. An old episode came on - the one where the crew of the USS Enterprise visited a society that had modeled itself after Chicago gangsters of the 1920s. Kirk and Spock dressed up in pinstripe suits and held court as tough guys.
Watching, Shatner was more pleased than he expected.
"I haven't seen myself playing Captain Kirk in a long, long time," he says. "And I watched it now, from my perspective of 40 years later, and I thought, `You know, that's rather good.' It's a starship captain trying to do the accent, the Noo Yawk accent, trying to play tough, trying to be one of the guys. It's not quite right, but it's what a starship captain would have done - a decent imitation, enough to fool those guys but not the audience."
Shatner won't be playing Kirk in the upcoming reboot of "Star Trek" directed by J.J. Abrams. Leonard Nimoy plays an aging Spock, but the Jim Kirk character - a young version - is portrayed by actor Chris Pine. Shatner has said he's sad but not angry at the decision, which springs from the killing off of Kirk in the 1994 film "Star Trek Generations."
The recent late-night TV watching got Shatner thinking, though, about the character of Kirk and how it has endured.
"That was a good hero," Shatner says. "He made decisions. He was forceful. He was compassionate. He was the instigator. He fought hard and long physically and emotionally. He carried the dilemma of whether to intrude or not to intrude. It was all the classic forms of good Greek playmaking: The hero has the dilemma and resolves the dilemma."
Even the series' renowned cheesy production design, done on an increasingly tight budget through the show's 1966-69 run, didn't put him off.
"The actors were wonderful. And I didn't care about the sets or anything like that or the cheesy spaceship," Shatner says. "I think that's what happens in `Star Trek.' Your eye goes past all the faults because you're concentrated on the actors and the plot."