Beholder

The Beholder is a Pain Elemental variant in Doom RPG and Doom II RPG. When killed the Beholder explodes releasing two Phantoms.

Etymology
"Beholder" is a name of the Dungeons and Dragons monster appearing as a floating head with a cyclopic eyeball and fang-filled mouth, hence the said Doom RPG monster's design.

Its name is also a term describing a person who sees/observes someone or something.