Whitewashing in film is when either 1) white actors play characters of color and pretend to be of the character’s racial / ethnic heritage or 2) the story itself is changed and characters of color are made white. This has long been a problem, but has reignited recently with casting of films such as Aloha, Ghost in the Shell, and Doctor Strange.
In the case of the film Hell Boy, actor Ed Skrein decided to back out of his portrayal of Major Ben Daimio. He released the following on twitter concerning his decision:
Casting characters of color with actors of color can also be contentious. In the case of The Hunger Games, the casting of Amandla Stenberg and Lenny Kravitz, casted as Rue and Cinna respectively, resulted in a racist twitter backlash. Readers of the book assumed these characters were white, despite descriptions to the contrary. Similarly, the casting of black actress Noma Dumezweni as adult Hermione in the Harry Potter play was met with racist reactions.