Rex (Fallout: New Vegas)

Rex (full designation of Cyber-Hound Mk. III, LEO Support Model, Serial Number B955883) is a 209 year old cyberdog living in Freeside in 2281. He is owned by the King. He hates rats and will immediately go for one if he sees one. He also doesn't like hats, or people who wear them, and it's unknown why, although the King says it might be because "hat" sounds like "rat".

Background
Rex is a cybernetic dog that has been around since pre-War times. He was used by the Denver Police Department and Caesar’s Legion before being mostly blown up during the Battle of Hoover Dam. Since then, he's been the loyal pet of The King of The Kings in Freeside. Capable of sniffing out loot and taking a large amount of punishment. He can become your companion during the quest Nothin' But a Hound Dog. After the quest he will become permanent.

Appearances
Rex appears in Fallout: New Vegas.