Now if they can just get Mark Hamill.
I hear hey may be a tad busy at the moment.
Well, a different reality's version of the same character, but still, that's awesome. That's pretty unusual, for the same actor to play a character in two different continuities. Well, it's happened a lot in animation (e.g. Olan Soule and Casey Kasem playing Batman and Robin for both Filmation and Hanna-Barbera, and Steve Blum and Fred Tatasciore playing Wolverine and Hulk in multiple Marvel animated realities), or in live-action characters reprising their roles in animation (e.g. Adam West and Burt Ward playing Batman and Robin in the second Filmation cartoon, or Clark Gregg playing Coulson in the Disney XD Marvel shows), but it's less common in straight-up live action. There's Dame Judi Dench playing M in the old and rebooted James Bond continuities, and Bob Hoskins played Smee in both Hook and Neverland. But those are about it, as far as I know.
For animation, Hamill played the Trickster in both the Flash TV series and in a brief appearance on JLU. Plus of course Conroy has voiced Batman in several different continuities.
Would Michael Gough and Pat Hingle count? They both played the same characters in the four Batman movies, half of which may or may not have actually been in continuity with the other half.
Off the top of my head I suppose there's also James Earl Jones who played Admiral Greer in the first three Jack Ryan films, but again the continuity (beyond the Ryan character) between 'Hunt for Red October' and 'Patriot Games' is unclear.
A bit obscure, but after a quick google it appears James Garner played Wyatt Earp in both 1967's 'Hour of the Gun' and 1988's 'Sunset'. Alan Hale, Sr. played Little John in no less than three different versions of Robin Hood in 1922, 1938 and 1950.
I suppose there's Ralph Bellamy and Don Ameche who played Randolph and Mortimer Duke in 'Trading Places' then later showed up as the same characters in 'Coming to America', though that's more along the lines of a joke cameo and it's implied that both films are in continuity. Incidentally that movie had James Earl Jones (again!) and Madge Sinclair who would both later play essentially the same roles in 'The Lion King'.
I think there's also a bunch of actors who portrayed the same historical figure (i.e. Lincon, Hitler, Napoleon, Elvis, various other presidents and monarchs) in several unrelated projects, but I'm not sure they counts as they're hired because they're close physical matches. Then there's the various and sundry incarnations of popular characters like Dracula and Sherlock Holmes who have sometime had the same actor play the role, but not always in direct (or at least, not "clear") sequels.
