Unrivaled Belle (foaled 2006) is a gray/roan American Thoroughbred racehorse owned and bred in Kentucky by Gary Seidler & Peter Vegso. She is a daughter of champion sire and champion racehorse Unbridled's Song, a descendant of the very influential sire Mr. Prospector, out of the Grade II winner (Bertrando). She was listed as sold for $260,000 at Keeneland September.