Ursa is one of General Zod's cronies, a villain from the Superman comics and major villain in the movie Superman II. She is an evil Kryptonian, and on Earth has all of Superman's powers, including super strength and the ability to fly.
In "Lethal Weapons", Ursa, Zod, and Non were seen in The Drunken Clam during the time when Peter was starting fights with the New Yorkers so Lois Griffin would beat them up. When Peter said "Krypton sucks", Zod and his gang attacked him, but Lois threw all three of them (first Non, then Ursa and Zod simultaneously) into the Phantom Zone, where they drifted off into space much like the beginning of the movie, Superman.