Selfless Knights are variants of Knights appearing in both The Binding of Isaac and the Rebirth remake. They possess with a mouth wide agape similar to a Maw's expression. They have Isaac's face on the back of their heads instead of a brain.
They behave just like regular Knights, except they advance towards Isaac at a higher speed if detected. They are commonly found in Sheol, but will occasionally replace regular Knights as champion version in previous floors, where killing them will drop a Pick Up. They are very rarely found in areas all the way up to the Caves/Catacombs.