Catoblepas (CR 6)

Huge Aberration
Alignment: Always neutral evil
Initiative: +1 (Dex); Senses: darkvision 60 ft., scent, Listen +3, and Spot +3


AC: 19 (-2 Size, +1 Dex, +10 natural), touch 9, flat-footed 18
Hit Dice: 6d8+30 (57 hp)
Fort +7, Ref +3, Will +6
Speed: 30 ft.
Space: 15 ft./10 ft.
Base Attack +4; Grapple +20
Attack: Tail slam +10 melee; or ray +3 ranged touch
Full Attack: Tail slam +10 melee; or ray +3 ranged touch
Damage: Tail slam 1d6+12 plus stun
Special Attacks/Actions: Death ray, Stun
Abilities: Str 26, Dex 13, Con 21, Int 2, Wis 13, Cha 8
Special Qualities: -
Feats: Improved Bull Rush; Improved Overrun; Power Attack
Skills: Jump +10, Listen +3, Spot +3, and Survival +3
Advancement: 7-12 HD (huge), 13-18 (Gargantuan)
Climate/Terrain: Any swamp
Organization: Solitary, pair or family (3)
Treasure: 1/10 coins, 50% goods, 50% items

Source: Monster Manual II