Warhammer 40k and Warhammer Fantasy character. One of the four Chaos (Warhammer) Gods, representing sorcery, ambition, trickery, and change.
His form is ever-shifting, but he is typically represented as a monstrous humanoid with gangly limbs, no head, and a deformed face set in his chest.
Alternatively, he may be drawn to resemble one of his Daemons, as a giant anthropomorphic blue bird.