Dan Kobachesky

 was a resident of Vault 92 and the one who provided Gordie Sumner with the weapon the shopkeeper locked in his safe in exchange for certain unspecified items.

Background
His role in the Vault is unknown save for the fact that he belonged to a department which had access to weapons. Gordie assured him nobody would be easily be able to trace the weapon back to this department, implying that Kobachesky was lacking authorization for this deal.

Appearances
This character is mentioned in Fallout 3 but does not actually appear in the game.