Dr. Keats is Grover's family doctor in the book A Visit to the Sesame Street Hospital. Grover's Mommy takes her son to him when Grover complains of a sore throat.
Dr. Keats announces that Grover needs to have his tonsils out, which will require an operation at the hospital. Grover is worried and scared, so Dr. Keats recommends that he and his mother visit the hospital to see what it's actually like.
He is a self caricature of illustrator Joe Mathieu.