(n.) One in charge of the performances (as of horses) within the ring in a circus.

MC acrobat aerialist auteur ballyhoo man bareback rider barker callboy circus artist clown costume designer costumer costumier director emcee equestrian director equilibrist exhibitor flier high-wire artist impresario juggler lion tamer makeup man master of ceremonies playreader producer prompter scenewright set designer showman slack-rope artist snake charmer spieler stage director stage manager sword swallower theater man theatrician ticket collector tightrope walker trapeze artist tumbler usher usherer usherette