Monty (voiced by Steve Zahn in Stuart Little 1 and 2, André Sogliuzzo in Stuart Little: The Animated Series and by Rino Romano in Stuart Little 3: Call of the Wild) is a grey tabby cat who is Snowbell's best friend and a former member of Smokey's alley cat gang.
Smokey (voiced by Chazz Palminteri) is a dark gray alley cat who is the main villain of the first film and the leader of the alley cats.