.Stephen «tWitch» Boss, Matthew Morrison and JoJo Siwa have been tapped as the new judges for season 17 of Fox's returning dance competition show, the network announced Monday. Longtime host Cat Deeley returns to emcee the new season, which is set to kick off Wednesday, May 18 after the finale of features dancers between 18 and 30 years of age showcasing their talents in various dance styles, including contemporary, tap, hip-hop, ballroom, animation, breaking and more.