Seagrave Holmes

 is a merchant in Rivet City who runs Rivet City Supply at the Marketplace. He deals in random junk and weapons.

Bannon the owner of Potomac Attire believes that Seagraves is trying to take over his seat in the city council, and ask you to find incriminating evidence, wich can be found in Seagraves Room.

However, should you decide to confront Seagraves with it, you can use it to remove Bannon from the council and instate Seagraves as a council member.

If you are working on the Wasteland Guide quest, he is one of the persons to talk to in finding out the History of Rivet City

Apperances
 only appears in Fallout 3.