Glee is an American musical comedy-drama television series that airs on Fox in the United States. It focuses on the William McKinley High School glee club New Directions competing on the show choir competition circuit, while its members deal with relationships, sexuality, and social issues. The initial main cast encompassed club director and Spanish teacher Will Schuester (Matthew Morrison), cheerleading coach Sue Sylvester (Jane Lynch), guidance counselor Emma Pillsbury (Jayma Mays), Will's wife Terri (Jessalyn Gilsig), and eight club members played by Dianna Agron, Chris Colfer, Kevin McHale, Lea Michele, Cory Monteith, Amber Riley, Mark Salling, and Jenna Ushkowitz. For the second season, formerly recurring cast members Mike O'Malley, Heather Morris, and Naya Rivera were promoted to the main cast. For the third season, Harry Shum, Jr. and Darren Criss were promoted from recurring to the main cast, and both Gilsig and O'Malley were removed from star billing, though the latter is again in the recurring guest cast. For the fourth season, Chord Overstreet was promoted from recurring to the main cast, and both Mays and Agron were removed from star billing, though they have both appeared and are being credited in the recurring guest cast.