A terrifying and dangerous creature.
A bizarre or whimsical creature.
The children decided Grover was a cuddly monster.
A cruel or antisocial person, especially a criminal.
Get away from those children, you meatheaded monster!
A horribly deformed person.
A badly behaved child, a brat.
Sit still, you little monster!
Something unusually large.
Have you seen those powerlifters on TV? They're monsters.
A prodigy; someone very talented in a specific domain.
That dude playing guitar is a monster.
A non-player character that player(s) fight against in role-playing games.
To make into a monster; to categorise as a monster; to demonise.
To behave as a monster to; to terrorise.
To harass.