Pre TOS appearances...

[A beaker full of death]

And then there was the American Indian experiment...

[yt]http://www.youtube.com/watch?v=IghwK0WYytU&feature=related[/yt][yt]http://www.youtube.com/watch?v=ZPEmUkhIoGc&feature=related[/yt]

 

[Kinggodzillak]

And The Man from UNCLE episode with Shatner and Nimoy (in a smaller role), The Project Strigas Affair.

James Doohan appeared on UNCLE a few times too. There was also an episode in the second series which featured both Ricardo Montalban (Khan) and John Winston (Lt Kyle), although they didn't have any scenes together, and occasionally you'd see Lt Hadley or Lt Brent somewhere in the background...

 

[digger]

I remember about 4 years ago I was watching an original Twilight Zone episode with my father. I forget the name of the episode.

But my father and I, who are both HUGE Trek fans--of all series--kept looking at this one guy that looked so familiar. We just couldn't place where we knew him from.

When the credits came on screen, it turned out it was James Doohan. What's funny to me about this story is that it looked exactly like him--it was only a few years before Trek. But since the Twilight Zone episode was black and white and Doohan was wearing regular clothes, it just didn't click in our heads until we saw the name in the credits.

 

[Potemkin_Prod]

Heh-heh, iirc, Kor's aide from "Errand of Mercy" ended up as the Lobster Man on Voyage to the Bottom of the Sea. And Stanley Adams was the Giant Carrot Man on Lost in Space.

 

[Ssosmcin]

Jimmy Doohan did two episodes of Voyage to the Bottom of the Sea (Hot Line and Hail to the Chief) and auditioned for the role of Chief Sharkey shortly before being hired for Trek.

George Takei also appeared on Voyage in The Silent Saboteurs.

 

[ToddPence]

George Takei from "The Twilight Zone". This episode has not been seen on TV since it first aired, although it has been released on video and DVD.

Here's a couple from "The Fugitive". The first with Jimmy Doohan. The second with DeForest Kelley.

And, of course, we can't forget that Shatner was on "The Fugitive", too.

Here's a couple of more with Kelley, from separate episodes of "Route 66" . . .