[atvcatole]

I think it's more common when books are adapted to TV/movies, so it's not as obvious as when they change historical characters or characters from other or older visual media. Often they change the location to North America/Europe and change the characters "organically" as well.

Anyway, here's the ones I can think of right away:

Ancient One in the Marvel movies to Tilda Swinton, although the comic character is kind of a racist stereotype, and would have issues in China, so they had good arguments for doing that change.

Staying in the comic universe, Bane and Ra's al Ghul in Batman movies.

Related to the first one; Benedict Cumberbatch plays Khan in the new Star Trek.