Jessalyn Gilsig as Kayley (voice)

Andrea Corr as Kayley (singing voice)

Cary Elwes as Garrett (voice)

Bryan White as Garrett (singing voice)

Gary Oldman as Ruber (voice)

Eric Idle as Devon (voice)

Don Rickles as Cornwall (voice)

Jane Seymour as Juliana (voice)

Céline Dion as Juliana (singing voice)

Pierce Brosnan as King Arthur (voice)

Steve Perry as King Arthur (singing voice)

Bronson Pinchot as Grifin (voice)

Jaleel White as Bladebeak (voice)

Gabriel Byrne as Lionel (voice)

John Gielgud as Merlin (voice)

Frank Welker as Ayden (voice)

Jack Angel as Additional Voices (voice)

Sarah Freeman as Young Kayley (voice)

Sherry Lynn as Additional Voices (voice)

Mickie McGowan as Additional Voices (voice)

Linda Harmon as Singing Voice (voice) (uncredited)