On Dallas Donna Reed played Miss Ellie during the season which was supposed to have been a dream, while Barbara Bel Geddes played the part before and after that. Two actors played Gary, the oldest son. Digger Barnes, the father of the Victoria Principal and Ken Kercheval characters, was played at various times by Keenan Wynn and David Wynn. The show had so much turnover that Ken Kercheval, Patrick Duffy and Larry Hagman are said to have been the only actors who appeared in every season–and Duffy’s appearance in the “dream season” was limited to a brief appearance in the shower in the last episode.
The oldest son on Eight is Enough was played by two different actors. IIRC, the first one was Mark Hamill, who played Luke Skywalker in the first three Star Wars films.
Veteran film star Sylvia Sydney played Mother Carlson, the owner of the radio station, in the first episode of WKRP in Cincinnatti. In a later season there was an episode with a flashback to the scene in the first episode in which Tim Reid–Venus Flytrap–was hired at the station. The scene was reshot with the actress who played Mother Carlson throughout the series.
There were two pilots for the series which became Leave it to Beaver. In the first, called It’s a Small World, the character of Wally was played by an actor who was closer in age to Jerry Mathers. Richard Deacon appeared in the episode, but not as Lumy Rutherford’s father; rather, he played a business-man who likely would not have been a recurrent character. Casey Adams, a character actor who played wise-cracking, smart-ass, vaguely sleazy parts in numerous films in the 50s was Ward; he came across as Hugh Beaumont’s evil twin.
Eddie Haskell’s father was played by two different actors. The part of Lumpy Rutherford’s mother, never a prominent role, was played by, I believe, three different actresses, one of them being Madgell Barrett, who had parts in Star Trek and in Star Trek: The Next Generation. (In the latter show she was Counsellor Troi’s mother and the voice of the shipboard comupter).
The way that Blofeld’s part kept getting recast always reminded me of the way no actor played Professor Moriarity twice opposite Basil Rathbone in the Sherlock Holmes b-movies. In the first production, which, I believe, was released by Twentieth Century Fox, he was played by George Zucco. In Sherlock Holmes and the Secret Code, a universal release, he was played by Lionel Atwill, who did not seem to put up much of an effort. In The Woman in Green, another Universal picture, he was portrayed by Henry Daniell.
Daniell appeared in several other roles in the course of the twelve Universal films. In the Voice of Terror he was the head of British Intelligence. In Sherlock Holmes in Washington he and Zucco were Nazi Spies. So was Ian Wolfe, who likewise played a slew of parts in the films.
The actor who played James Garner’s father in the pilot for The Rockford Files looked, and acted, very differently from Noah Beery Jr., who had the role throughout the series.