Formal:
* Чудовище (chudovische) - This is the most common and formal word for monster. It refers to a creature that is grotesque, frightening, and often supernatural.
Informal:
* Монстр (monstr) - This is a more informal word for monster, often used in colloquial speech and writing.
* Урод (urod) - This word literally means "deformity" and is used to describe a creature that is physically repulsive.
* Чудовище (chudovische) can also be used in informal contexts.
Specific Types of Monsters:
* Зверь (zver) - Beast, animal, can also be used for a monstrous creature.
* Дьявол (dyavol) - Devil, demon.
The best translation will depend on the context and the specific type of monster you're referring to.