<Li> Dakota Fanning as Sally Walden, Joan's dull, well - behaved, and rule - obeying daughter . </Li> <Li> Kelly Preston as Joan Walden, Conrad and Sally's mother, and a workaholic real - estate agent . </Li> <Li> Alec Baldwin as Larry Quinn, the Waldens' pompous, lazy, unemployed next - door neighbor . He is revealed to be allergic to cats, steals food from the Waldens and gets away with it, and is determined to both marry Joan for her wealth and send Conrad to military school to straighten up his behavior . </Li> <Li> Amy Hill as Mrs. Kwan, an elderly Taiwanese woman who gets hired to watch the kids, though she sleeps through her job . Her weight and sleep serves as a running gag . </Li>

Who is cat in the hat played by