He's the biggest teen heartthrob on the face of the planet -- JUSTIN BIEBER is here! On the day his brand new album "Under the Mistletoe" is released, the pop phenomenon is under our studio lights for an incredibly special appearance. He'll tell all about his life, his career, and his girlfriend, Selena Gomez -- one of the most talked about relationships in Hollywood! Then, the follow-up to the most touching surprise in Ellen Show history. SHERRIE GAHN, the principal with a heart of gold, is telling Ellen about how the show has changed her life. It's all happening this Tuesday!