Champions

From UOGuide

Champions is the name given to the boss monsters of Champion Spawns. Each one is in some way linked to the type of spawn being fought. For example, Rikktor, whose spawn includes Dragons, is a super-hard Ancient Wyrm. Baracoon, the Champion of the Vermin Horde spawn, is a "pied piper" type. In Felucca, the highest-end Power Scrolls come from Champions. In all Facets, the death of a Champion is necessary to spawn Champion Spawn Artifacts, and certain rare pieces from Item Sets can spawn on their corpses.

For more information, see Champion Spawns.