The cast was revealed on Wednesday on ABC.
The show has reached an increasingly older audience, but it has added more youth with reality stars Nicole "Snooki" Polizzi of Jersey Shore and Ozzy's kid Jack Osbourne.
Harper has defied odds with her survival since being diagnosed earlier this year with brain cancer.
Other contestants are Bill Nye, the Science Guy; Pretty Little Liars actor Brant Daugherty; former football star Keyshawn Johnson; singer and actress Christina Milian; actress Elizabeth Berkley; High School Musical actor Corbin Bleu; Glee actress Amber Riley; country comic Bill Engvall; and King of Queens actress Leah Remini.