a few more:

How about Natalie Wood as the Puerto Rican Maria in "West Side Story?"

Didn't Rock Hudson play an Apache in "Taza, Son Of Cochise," or some other of those old 1950s/early 60s movies about the cowboys and the Indians?

Not really miscasting, but in the film "Carmen Jones," the studio, in their brilliance, chose to dub the voices of Harry Belafonte and Dorothy Dandridge with some operatic sounding voices, instead of using their own fine voices. Not only was the dubbing totally unnecessary, but the voices didn't fit the actors (or the feeling of the script) and it was done very badly, to boot.

Almost every actress who has ever been cast in a movie version of "Jane Eyre" has been too pretty to really do the role of the "plain" heroine convincingly.