Beholder

Beholder is a very dangerous hostile creature usually found in underground hidden rooms (often with guardians) of all worlds. It can also spawn from monsters portals, both in single and multiplayer games. It does not appear in any biome.

Mobility
Despite its appearance, the beholder cannot fly. It floats depending on background and foreground walls (much like giant ants and hens).

It can fall from a ten block height without being hurt.

Tips
Despite its bestiary description, it is not very dangerous, but it does have lots of health, making it more annoying.

It's recommended to use bows if dwarfs are going to kill him if they are not well armored yet. Since it is large, it can be shot in safety from narrow passageways. Alternating shooting with running away is also a possible strategy in early game.

The beholder likes to push dwarfs and his allies that are attacking him backwards, so make sure they can't fall down a pit.

Trivia

 * The beholder's appearance and behavior in Craft the World is mostly copied from the original in Dungeons & Dragons.