Urso is an animal from Mongo that King Vultan keeps as a pet in the Sky City. Urso, who resembles an Earth bear with white stripes painted on his hide, looks frightening but is apparently a tame pet. King Vultan brings Urso into his private chamber in chapter 5 of the Flash Gordon serial, to frighten Dale Arden.
Dale is terrified, and backs up against the wall, but Urso doesn't do her any harm. When Vultan orders him to "begone", the beast calmly walks out. Vultan swats the animal on the behind as it's leaving the room, and it doesn't flinch.