Harkness

 is the Rivet City security chief and belongs to the Rivet City Ruling Council. He is the first person you encounter upon finding Rivet City, and will demand that you state your business in Rivet City before he allows you to enter.

Unbeknownst to him, he is really an escaped android from the Commonwealth. In his search for somebody to reconstruct his face and assist him with wiping and replacing his memories, so nobody would recognize and catch him, he ended up in Rivet City where the job was finally done by Pinkerton.

Harkness wears a Rivet City Security Uniform armor, and wields a Chinese Assault Rifle. He's somewhat tougher than the standard Rivet City Security Guards, being able to survive a couple more hunting rifle headshots than normal.

He is considered a plot-critical NPC, and thus cannot be killed untill the quest "The Replicated Man" is complete. Before that, he can only be knocked out. Harkness seems to remain unkillable even after The Replicated Man is completed, although this may be a bug caused by acquiring both rewards for the quest (by obtaining the rewards from Harkness and Zimmer, then killing Zimmer to prevent him from taking Harkness).

Appearances
Harkness appears only in Fallout 3.

Location
During the day, Harkness can be found outside Flak and Shrapnel's weapon store in the Rivet City marketplace. He can also be located on the top floor of the Bridge Tower from 12:00 Midnight to 6:00AM.

Bugs

 * In one instance, Harkness was permenantly frozen in the position the player first encounters him. This may however, only happen if the Scientific Pursuits quest is skipped by saving James from Vault 112, without ever travelling to Rivet City, and James returns to Rivet City without the player. The player will still be able to interact with Harkness, but he will not move from his position at the end of the extended bridge.
 * This can be fixed by completing The Replicated Man quest by informing Harkness of his true identity.
 * Harkness can actually be pushed off the deck of Rivet City. When he lands in the water, he is stuck there and never returns to his post. This happened to me after I completed both Scientific Pursuits and The Replicated Man on the PS3 version of the game.

Trivia
Harkness could possibly come from the creators continual references of Doctor Who characters, in this case, Captain Jack Harkness, a time agent from the future who can not die. Furthermore, Captain Jack has had some of his memories removed, rather like Harkness. Could also be from Huckleberry Finn, when the character Ben Harkness is described as "half a man".

Related quests

 * The Replicated Man