Ballet Master

Ballet Master (also Balletmaster, Ballet Mistress, Premier Maître de ballet or Premier Maître de ballet en Chef) is an employee of a ballet company. The Ballet Master is responsible for keeping the dancers in the company to a high level of competence. 
Ballet masters (or ballet mistresses for women) teach the daily company ballet class. They rehearse the dancers for both new and old ballets in the company's repertoire. The artistic director of a ballet company may also be called its ballet master.