Randall.

All of them !! Interesting how the duology has 4 different kinds of villains: -

1) Waternose - Twist villain and corporate businessman.

2) Randall - Henchman or subordinate.

3) Worthington - High School Bully

4) Hardscrabble - Creepy college principal

Randall Boggs🟣😈is The Greatest Main Villain Antagonist Pixar's Monsters inc Franchise.