Kuo-toa

The Monster Manual describes Kuo-toa as “fishlike humanoids that once inhabited the shores and islands of the surface world. Long ago humans and their ilk drove the kuo-toa underground, where they dwell in everlasting night. Kuo-toa can no longer abide daylight.”

Beholder

Beholders are described in the Monster Manual as “the scourge of sentient creatures across countless worlds.”

Owlbear

Owlbears are described in the Monster Manual as “a monstrous cross between giant owl and bear, an owlbear’s reputation for ferocity and aggression makes it one of the most feared predators of the wild.”