One of the most clever aspects of the Doctor Who series, from a producer's viewpoint anyway, is that it is inscribed into the character that he can be replaced by other actors. This is one of the reasons why the show has such a long life. I've been trying to think of similar situations in which different actors end up playing the same character. Not an actor coming on to an establlished show to play a new character in the same position (as in Mission Impossible) or a new actor playing a younger version of an older character, but different actors playing the same person. All I can think of is Dick York quiting Bewitched and giving way to Dick Sargent. I'm sure that in the half century plus of television history there must be other examples. Anyone have any ideas?

I know that on soap operas, they'll occasionally have substitute actors step in for the regular actor, as the same character, for one reason or another.

Lecy Goranson was replaced as the elder daughter on ROSEANNE for a season or two by SCRUBS' Sarah Chalke, but returned later in the run. (Chalke had a funny cameo in the Halloween episode the year Goranson returned.)

Also, on BEWITCHED, didn't the meddling neighbor, Gladys Kravitz, also get recast? Maybe it was her husband.

On THE JEFF FOXWORTHY SHOW, the actress who played the wife in the first season got replaced by another actress in the second season. I never watched the show, but I remember this because there was a commercial for the show that spoofed this fact.

On the TV show TITUS, Christopher Titus's mom was played by a different actress each season, that is, when you saw her face. That made a total of at least 3 different actresses playing the same character.

On Petticoat Junction Billie Jo was played by Jeannine Riley for the first two or three seasons then Gunilla Hutton for one season then Meredith MacRae after. Bobbi Jo was also replaced: Pat Woodell then Lori Saunders.

On The Munsters Beverley Owen initially played Marilyn then left and was replaced by Pat Priest.

Some examples from All My Children: Opal was originally Dorothy Lyman then brought back played by Jill Larson. Nina was played by a couple of different actors. Alicia Minshew is playing Kendall who I think is the same character Sarah Michelle Gellar played when she was on the show.

I also think when Meg Ryan was on As the World Turns she was playing a character that others had done before her. But I don't think after since I seem to remember her dying on the show.

There must be numerous examples of changes to infrequent supporting characters such as Julie Newmar and Eartha Kitt both playing Catwoman on Batman. And even more for casting changes from the pilot to actual series (such as Willow on Buffy).

And oh yeah - Lois Lane was replaced on the George Reeves Superman show. I think this was even alluded to in Hollywoodland.

Actually the Doctor Who changes are more like the Mission Impossible comparison than the others in this thread -- he isn't an actor swap-out, he's a dramatic replacement, with an entirely different personality, in the same position. One day he's Jon Pertwee, the next, Tom Baker.

The most similar change to this I think was ITV's Robin of Sherwood in the mid-eighties, where a new person became Robin mid-way, a change that was explained in the context of the show, and therefore established a precedent that could be continued as necessary (though in the event, the show didn't last long enough to test that theory).

Well, there was the swap of Will and Holly's dad, Spencer Milligan, for "Uncle Jack" in the third (and final) season of the original LAND OF THE LOST.

Plus, Ian Hendry>Jon Rollason/Julie Stevens/Honor Blackman>Diana Rigg>Linda Thorson as John Steed's regular partners on THE AVENGERS.

The Doctor is a weird case, sort of a mishmash of both types of replacements. He looks completely different after each regeneration, has a completely different personality, a different style of dress, etc.; but at the same time, he's the same person -- has the same set of memories, the same history with those around him, etc. The best comparison I can think of is if you watched a movie and its 9 sequels, each of which is helmed by a different creative team, and each of which stars a different actor in the lead role.