The Cat in the Hat (also known as Dr. Seuss' The Cat in the Hat) is a 2003 American family comedy film directed by Bo Welch. It is based on the 1957 Dr. Seuss book of the same name. The film stars Mike Myers in the title role of the Cat in the Hat, and Dakota Fanning as Sally. Sally's brother (who is unnamed in the book and the 1971 TV special), Conrad, is portrayed by Spencer Breslin. The film is the second feature-length Dr. Seuss adaptation after the 2000 holiday film How the Grinch Stole Christmas.

The idea was originally conceived in 2001, with Tim Allen initially cast as the Cat, but he dropped his role due to work on The Santa Clause 2, and the role was later given to Myers. Filming took place in California for three months. While the basic plot parallels that of the book, the film filled out its 82 minutes by adding new subplots and characters significantly different from the original story.

Released on November 21, 2003, in the United States, the film grossed $134 million worldwide.[3] After the film's release, Seuss' widow, Audrey Geisel, decided not to allow any further live-action adaptations of Seuss' works to be produced, and as a result, a planned sequel based on The Cat in the Hat Comes Back was scrapped.