Related Clues:
- Luthor and Zod, to Superman
- Agents of undoing
- Fearsome foes
- Tough opponents
- Joker and Riddler, to Batman
- Harry Potter and Lord Voldemort, e.g
- Sinestro and Professor Zoom, in their respective universes
- You can't beat them
- Watch people on the up eclipsing second greatest rivals
- Usually victorious rivals
- Sworn enemies
- Rivals who often win out
- Superheroes always have them
- They're usually unbeatable
- Foes that seem impossible to beat