Beholder

A beholder is a powerful creature that originated in the Far Realm.

Description
An evil aberration, a beholder's body consists of a hovering skull with a wide and toothy maw, an enormous central eye, and ten independently moving eyes at the end of their own eyestalks.

Abilities
Note:  This section does not specify the copywritten monster ability details, which are available in the D&D 5th edition Monster Manual''.
 * Immunities:  The "prone" condition.
 * Senses:  Darkvision.
 * Languages:  Deep Speech; Undercommon.
 * Antimagic Cone:  The beholder can negate magic within a 150-ft cone in front of its central eye.
 * Also negates the effects of its own eye rays within that area.
 * Bite:  The beholder can bite at a target with its giant, toothy maw.
 * Eye Rays:  A beholder has ten different eyes attached to its head, each of which can emit a different magical ray at separately selected targets.
 * Legendary Action:  A beholder can use one of its eye rays at the end of another character's turn.

Known Beholders

 * K'Varn came to the Material Plane through a rift between dimensions, bringing a Horn of Orcus with him.
 * Unknown beholder (possibly called Yar'Voss based on what its servant said as it died) in.

Trivia

 * Due to Beholders being Product Identity of Wizards of the Coast under the Open Game Licence, they are replaced with unspecified extraplanar aberrations in the Tal'Dorei Campaign Setting Guide.