As in Mister Burke from Fallout 3? If so, he is a quest NPC that hires you on to activate and detonate the bomb in Megaton. He resides in Tenpenny Tower to the Southwest of Megaton, but you will find him for the first time sitting in the inn inside of Megaton. He is directly to your right as you enter the front door. Following his request will give you loads of "bad" karma, a key to your very own hotel suite within Tenpenny Tower, and between 500 and 1000 caps.