In the shorts and earlier episodes, Castellaneta voiced Homer with a loose impression of Walter Matthau; however, during the second and third seasons of the half-hour show, Homer's voice evolved to become more robust, to allow the expression of a fuller range of emotions. He has appeared in other media relating to "The Simpsons"—including video games, "The Simpsons Movie", The Simpsons Ride, commercials, and comic books—and inspired an entire line of merchandise. His signature catchphrase, the annoyed grunt "D'oh!", has been included in "The New Oxford Dictionary of English" since 1998 and the "Oxford English Dictionary" since 2001.