Samuel (Fallout 3)

Samuel is a feral glowing ghoul, found behind Takoma Industrial, after reading the observation files on the monitor in Isabella Proud's camp. If the Lone Wanderer is wearing the ghoul mask when reading Isabella Proud's terminal, he may glitch and get stuck into the ruins nearby.

I found a glitch by Samuel where you can walk off map for miles on XBox 360. Good weapon testing ground.