monster

1a :  an animal or plant of abnormal form or structure a mythical monster a sea monsterb :  one who deviates from normal or acceptable behavior or character an immoral monster

2 :  a threatening force the same monster — Destiny … that rolls every civilization to doom — W. L. Sullivan

3a :  an animal of strange or terrifying shape visualize this scaleless monster, eight or nine feet long, sprawling in the shade by the side of the mud pools — W. E. Swintonb :  one unusually large for its kind That truck is a monster.

4 :  something monstrous; especially :  a person of unnatural or extreme ugliness, deformity, wickedness, or cruelty His father was a monster who beat his children for no reason.

5 :  one that is highly successful That movie was a monster at the box office.