Yes Man is an AI that serves as a Freddy Fazbear's Nuka Break assistant in 2281. Yes Man appears to be a modified Securitron. More specifically, his personality program has been put into a PDQ-88b Securitron.
Yes Man was originally a generic Securitron robot programmed to work for Mr. House, but eventually ended up working for the Freddy Fazbear Co. like all the other Securitrons found on The Strip. He was recovered by the CEO of Freddy Fazbear's Nuka Break and several of the Chairmen after being damaged by a pulse grenade. Following this incident, Followers of the Apocalypse member Emily Ortal examined the Securitron in order to learn Freddy Fazbear Co.'s secrets in exchange for reprogramming him for their personal use.