Classic Enemies:
* Lex Luthor: Superman's arch-nemesis, a brilliant scientist with an obsession with power and a hatred for Superman.
* Brainiac: An alien super-intelligence with a thirst for knowledge and a penchant for shrinking planets.
* General Zod: A Kryptonian military leader who is Superman's equal in power and has a vendetta against him.
* Doomsday: A genetically engineered monster with immense strength and a desire to destroy everything.
* Darkseid: A powerful god-like being who seeks to conquer the universe.
Other Notable Enemies:
* The Joker: While primarily a Batman villain, the Joker has occasionally targeted Superman as well.
* The Penguin: Similar to The Joker, the Penguin has occasionally clashed with Superman.
* Parasite: A being who can absorb the powers and life force of others.
* Bizarro: A flawed and twisted duplicate of Superman with the opposite personality and powers.
* Metallo: A cyborg with a Kryptonite heart, giving him the ability to challenge Superman physically.
* Livewire: An electrical manipulator with the ability to control electricity.
* Cheetah: While primarily a Wonder Woman villain, Cheetah has also gone up against Superman.
It's worth noting that Superman's enemies have evolved over time, with newer villains like Darkseid and Doomsday taking on increasingly significant roles in his mythos.