Protectron

Protectrons are robots that appear in Fallout 3 and Fallout: New Vegas.

Background
 As their name suggests, the protectron series of robot were devised primarily for protection and security operations of offices mostly, though their secondary programming is very modular and can be modified to make the Protectron perform many functions, such as acting as greeters, ticket collectors, bartenders, or even functioning as celebrity or historical figure impersonators. They were created by the RobCo corporation.