Thanos - Josh Brolin
Thanos is the biggest villain in the extensive Marvel Universe. He quite literally comes crashing down in Avengers: Endgame. His goal? To capture all of the infinity stones so he can erase the entire universe. Josh Brolin plays the major villain, which is actually somewhat visible despite the fact that his entire get-up is CGI.
The Joker - Heath Ledger
Even people who aren't major fans of the Batman franchise can agree that Heath Ledger is the best Joker in existence. He somehow perfectly captured the chaotic energy of the character, making him so realistic but outrageous at the same time. Ledger is only rivaled by Joaquin Phoenix, but they played two very different Jokers.