Gruber

 is a released slave and the champion of The Hole by 2277.

Background
Gruber was once a slave, but won a battle in The Hole and was set free. He became so bloodthirsty that he fought there again.

Interactions with the player character
Gruber's out for blood (yours, perferably), and will open fire as soon as the last round of the Hole begins. You'll need to kill him to finish Unsafe Working Conditions.

Behind the scenes
When translated in German, (Grube)r, means, "pit."

Appearances
appears only in the Fallout 3 add-on The Pitt.