Mahler (foaled April 14, 2004) is a racehorse sired by Galileo out of Rainbow Goddess. During his racing career, he was trained in Ireland by Aidan O'Brien, and he is owned by Sue Magnier, Michael Tabor and . His most notable victory was in the Group 3 Queen's Vase at Ascot Racecourse in Great Britain, although a more lucrative performance was to follow in the 2007 Melbourne Cup in Australia, where he finished third when ridden by . He now stands as a stallion at Coolmore's National Hunt breeding operation in Ireland.