Clifford's Really Big Movie is a 2004 American animated adventure film based on the classic PBS Kids TV series Clifford the Big Red Dog, itself an adaptation of the book series of the same name by Norman Bridwell. This film was directed by Robert Ramirez, produced by Scholastic Entertainment and Big Red Dog Productions, and originally released to theaters by Warner Bros. on February 20, 2004.

The film depicts a giant red Labrador Retriever named Clifford (John Ritter) running away and joining a travelling animal show known as "Larry's Amazing Animals" with his best friends. Larry Gablegobble (Judge Reinhold), the presenter of the animal show, doesn't allow animals who have owners, so they pretend their dog tags are fake. The film takes place in the fictional island of "Birdwell Island", which is the name is inspired by Norman Bridwell, the author of the books.

This was John Ritter's final theatrical film role as he died of aortic dissection on September 11, 2003. The film was dedicated to his memory, and it serves as the series finale, as no episodes aired after the film's release, though the show's spin-off Clifford's Puppy Days continued to air before concluding in 2006. It is currently the only theatrical film based on a PBS Kids TV series, not counting the films based on Sesame Street or Curious George.

The film notably depicts characters with sclera, in contrast to the books and TV series, which portrayed every character except the giant Clifford with black bead eyes.

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