James Garner starred as Bret Maverick for the 50s TV show but appeared as Marshall Zane Cooper in the 1994 film treatment.
Vanessa Redgrave played Anne Boleyn in the original film of * A Man for All Seasons* and played Thomas More’s wife in the TV (HBO?) remake.
The OP excluded cameos. If we include cameos we’ll have hundreds of examples.
Has anyone mentioned Ghostbusters? All four Ghostbusters plus Sigourney Weaver have cameos in the new movie. The late Harold Ramis appears as a bust.
In Supergirl the title character’s adopted mother is played by Helen Slater who was Supergirl in the movie. Her father is played by Dean Cain.
The Arrowverse is full of these. John Wesley Shipp plays the father of the Flash and also an alternate version of the Flash. In the cheesy series from the early 90s he was the Flash. Amanda Pays was his love interest and plays a character of the same name now.
Mark Hamill played the villain The Trickster in the old Flash series. He plays an older updated version of The Trickster in the new series.
None of those are cameos. All have been in multiple episodes.
Colm Wilkinson plays the Bishop in the Wolverine version of Les Miz. He originated the role of Jean Valjean in the English version of the play.
Not exactly what you’re looking for, but Ian Holm was Frodo in the BBC Radio adaptation of The Lord of the Rings, and then Bilbo in the Peter Jackson films.
Technically disqualified.
Cooper is revealed to be Maverick’s father, a role Garner played in the TV show.
Actually, unlike the Murnau original, Herzog’s Nosferatu actually calls the character “Dracula.” So no stretching involved. 
Dean Stockwell played Wilbur Whateley in the 1970 AIP film version of The Dunwich Horror. He played Dr. Henry Armitage in the 2009 TV movie remake.
True… except it is never established that James Garner is Bret Maverick Sr. or possibly Beau “Pappy” Maverick.
What, nobody’s mentioned Keven McCarthy, who was in both the 1956 and 1978 versions of Invasion of the Body Snatchers (albeit only briefly in the latter)? It was a big thing at the time!
I see Don Siegel was in the latter as well (also briefly, I think). He directed the original version.
Not the same but Lloyd Bochner is the lead in the Twilight Zone episode “To Serve Man.” In Naked Gun 2 1/2 his character is later seen in a panicked crowd yelling “It’s a Cookbook!”
Warning: OJ: - YouTube
Bill Mumy was Will Robinson in TV’s Lost in Space, and played Dr. Zachary Smith in the Netflix reboot.
Also, Jonathan Frid was Barnabus Collins in the TV version of Dark Shadows, and played a party guest in the Johnny Depp movie version.
Yeah, but he was basically playing the same character – the Guy On the Highway TRyinmg to Warn Everyone About the Invasion. I thought about it when I wrote the OP, but didn’t think it counted.
By the way, he played the same role AGAIN in Looney Tunes…Back in Action (2003).
I’m not looking for actors who played the same part in multiple versions of essentially the same film – I’ve done that thread already, and it has lots of entries.
Here are a couple that don’t quite fit, but are noteworthy.
Phil Silvers didn’t want to play Pseudolus, the lead character in A Funny Thing Happened on the Way to the Forum on Broadway because he thought it was too similar to his “Sergeant Bilko” character. And besides, nobody would buy a Romanm with glasses. Zero Mostel played tha character onstage and in the film.When they made the film, though, he played Marcus Licus (without glasses). Eventually, though, he did play Pseudolus in a stage version.
Lon Cheney, Jr. has the distinction of playing most of the Universal Classic Monsters . He originated The Wolfman (although Henry Hull had previously been The Werewolf of London), played The Mummy three times, the Frankenstein Monster once, and , if not Dracula, at least the Son of Dracula. He didn’t appear in a second version of a film he’d appeared in, though. He does come close, however, for taking on the role of the Frankenstein monster in Abbott and Costello meet Frankenstein on a day that Glenn Strange was unable to do the part. He was, of course, also playing Lawrence Talbot and The Wolfman in the same film, so he played multiple parts in the one movie.
I didn’t know that, thanks.
Michael Caine played Carter in the original “Get Carter”. And then played one of the guys Carter is after in the Sly Stallone remake of “Get Carter”. Not a huge role, but more than just a cameo.
Legendary martial arts actor Chia-Hui Liu (a.k.a. Gordon Liu) played masked gangster Johnny Mo in Kill Bill, vol. 1, but returned as a-hole master Pai Mei in Kill Bill, vol. 2. I found him not credible in the former role because I could not suspend my disbelief when Uma Thurman kicked his ass.
And I saw a production where he played Inspector Doppler.
Does Peter Capaldi qualify? - from Caecilius in “The Fires Of Pompeii” to the 12th Doctor himself.