Hitesh Rattan
Doctor Doom
Doctor Doom who was first introduced in The Fantastic Four: First Steps will be played by Robert Downey Jr.
Mephisto
Mephisto who was introduced in Marvel's Iron Heart will be played by actor Sacha Baron Cohen.
Galactus
Although not traditionally a villain, Galactus survives by eating planets. The character is played by Ralph Ineson.
Kang the Conqueror
Kang the Conqueror who is played by actor Jonathan Majors was first introduced in Loki's web series.
Thanos
The strongest villain which fans have seen on-screens, Thanos wiped out half of the world's population using the gauntlet.
Knull
Knull who is yet to be introduced in the MCU universe came into being following the destruction of the sixth iteration of the cosmos.
The Beyonder
The Beyonder is said to be one of the strongest MCU villains. At one point, The Beyonder obliterated the entire multi-verse.