Most actors either get typecasted or get associated with a single role (Hannibal Lecter anyone?) John Ritter use to say that if he got a Nobel Prize, as he walked up on stage to accept it they would play “Come and knock on my door”.
But a few do manage to get the Sylvester Stallone prize for being remembered for two totally separated characters, like Rocky Balboa and John Rambo.
Or Harrison Ford, with Han Solo and Indiana Jones.
Or on TV, William Shatner with James T. Kirk and Denny Crane.
Don Knots as Barney Fife and Mr. Furley.
Hugo Weaving as Agent Smith and Elrond.
Makes it a bitch trying to convince people to watch Priscilla, Queen of the Desert.
Pierce Brosnan-James Bond and Remington Steele.
Betty White as Sue Ann Nivens on The Mary Tyler Moore Show and as Rose Nylund on The Golden Girls.
David Hasselhoff as Michael Knight on Knight Rider, and Mitch Buchannon on Baywatch.
Hugh Laurie as Dr. House and Bertie Wooster
The OP took the best examples, but how about…
Bryan Cranston (Hal on Malcolm in the Middle and Walter on Breaking Bad)
Jim Backus (Mr. Magoo and Thurston Howell III)
The OP forgot to mention Neil Patrick Harris: Doogie Howser and Barney Stinson
Bea Arthur as Dorothy Zbornac(Golden Girls) and Maude Findlay( All In The Family/Maude)
Bob Denver: Maynard G. Krebs and Gilligan
Lorne Greene: Ben Cartwright and Commander Adama
Bob Newhart as Bob Hartley and Dick Loudon (though, I suppose technically they’re the same character).
Andy Griffith as Andy Taylor and Ben Matlock.
Buddy Ebsen as Jed Clampett and Barnaby Jones.
Rowan Atkinson as Edmund Blackadder and Mr. Bean
Ron Howard as Opie & Richie Cunningham.
Robbie Coltrane as Hagrid and as Dr. Fitz in Cracker.
Actually, if you go back far enough, he played Georgie Russel to Fess Parker’s Davy Crockett in the 1950s Disney series, which I think gave them idea to cast him Jed Clampett, since they were both Eastern backwoodsmen.
which, of course, leads us to:
Fess Parker as Davy Crockett and Daniel Boone
For me it’s the opposite - I saw Priscilla about a dozen times when it first came out. Now I can never quite believe Weaving as anyone but Mitzi.
Two and a half hours and no one has mentioned Harrison Ford as Han Solo and Indiana Jones?
whispers the OP
Robert Preston: Harold Hill (Music Man) and Toddy (Victor/Victoria).