Rooster Booster is a unique Lil' Scav in Borderlands: The Pre-Sequel. He only appears at the run-down St. Pancreas railway station located in Stanton's Liver.
Rooster Booster is the leader of the local Scavs and on his person carries explosives and a detonator. Vault Hunter must kill him to get those as they are needed to blow up the grinder and get some of its parts.