Beholder, Death Tyrant (CR 13)

Large Undead
Alignment: Always neutral
Initiative: +0; Senses: all-around vision and Spot +6
Languages: No language

AC: 20 (-1 size, +11 natural), touch 9, flat-footed 20
Hit Dice: 11d12 (71 hp)
Fort +3, Ref +3, Will +9
Speed: Fly 15 ft. (average)
Space: 10 ft./5 ft.
Base Attack +5; Grapple +9
Attack: Bite +4 melee
Full Attack: Bite +4 melee
Damage: Bite 2d4
Special Attacks/Actions: Eye rays +4 ranged touch
Abilities: Str 10, Dex 10, Con -, Int -, Wis 15, Cha 17
Special Qualities: antimagic cone, flight, single actions only, +2 turn resistance, undead traits
Feats: -
Skills: Search +4 and Spot +6
Advancement: 12-16 HD (Large); 17-33 HD (Huge)
Climate/Terrain: Any land and underground
Organization: Solitary
Treasure: Standard

Source: Forgotten Realms Campaign Setting

The death tyrant is an undead form of beholder akin to a zombie, though it retains some of the beholder's innate magical abilities.

A death tyrant appears as a rotting, mold-encrusted beholder. Gaping wounds - whether from injury or simply decomposition - expose the insides of its body, and it is either missing a few eyestalks or has a milky film covering some of its eyes. Because of its zombie like state, it moves and turns more slowly than other beholders, and it does not speak or understand language.