Batman's love interest switched actresses from Katie Holmes to Maggie Gyllenhaal in The Dark Knight. Sorry, Bruce Wayne, but that's not an upgrade.
The calm Don Cheadle replaced the crazy-eyed and sweating Terence Howard in the Iron Man series and subsequent MCU films. That's like switching from Red Bull to decaf.
Marvel finally found their (green) man with Mark Ruffalo, who looked better in ripped purple shorts than Eric Bana and Edward Norton.
Claire Foy wore the infamous back tat, taking over the Lisbeth Salander role from Rooney Mara in the Girl With the Dragon Tattoo sequel.
Genius impressionist/actor Ross Marquand (of The Walking Dead) put on the prosthetics to revive Captain America's nemesis in Infinity War. The face-melted Nazi was originally played by Hugo Weaving.
Bryce Dallas Howard swooped into the villainous Twilight role in place of Rachelle Lefevre for the third film. Talk about ginger-on-ginger crime.
Michael Gambon had to step into Sir Richard Harris' wizard shoes after the legendary actor's death before filming the first sequel.
It's rare to get the heave-ho during the shooting of a film, but that's exactly what happened to James Purefoy for V for Vendetta. His replacement? None other than Hugo Weaving.