Actor Michael J. Fox has joined the cast of Columbia Pictures’ “Stuart Little” as the voice of the title character, a mouse.Fox joins Geena Davis, Jonathan Lipnicki (“Jerry Maguire”) and British comedian Hugh Laurie (“Sense and Sensibility”) in a story about a family who adopts a mouse. Fantasy pic is based on the classic 1945 children’s book by E.B. White, adapted by M. Night Shyamalan. Stuart will be computer-generated. Rob Minkoff (“The Lion King”) is directing the pic, skedded for a Christmas 1999 release. Doug Wick and his Sony-based Red Wagon Prods. are producing. Exec producers are Jeff Franklin and Steven Waterman. Fox is repped by CAA.