Barbara Sternig, a family friend, says Castaneda died Thursday at a Los Angeles rehabilitation center after being treated for a neck injury.
The Los Angeles Times says Castaneda was believed to be 98. She came to prominence after appearing in the 1935 classic "Mutiny on the Bounty," a film that would be remade decades later starring Brando.
Castaneda was also known for roles in "Flying Down to Rio" alongside Fred Astaire, "Paradise Isle" and "Captain Calamity." She married Brando in 1960.