Deputy Weld

Deputy Weld is a Protectron robot that guards the gate of Megaton. As a note, if the player decides to massacre the residents of Megaton and attack Deputy Weld before entering the armory, another different robot, Deputy Steel, will appear (he resides in the armory, hence why he won't show up if you have already been in the armory and killed him).

Quotes

 * "Welcome to Megaton. The bomb is perfectly safe, we promise. Please hold for threat level assessment. Threat level minimal. Open the gates. Open the gates. Welcome to Megaton."

Appearances
Weld appears only in Fallout 3.