Bill Mumy was born Feb. 1, 1954, so he was 11 on Sept. 15, 1965, when the series premiered.
Will is 9 years old and a graduate of Camdo Canyon School of Science (No Place to Hide).
He can play the guitar (There Were Giants in the Earth and Castles in Space).
Will seems to have telekinetic powers (Wish Upon a Star, Space Circus and Space Destructors).
The Robot calls him "Master Will Robinson" (Treasure of the Lost Planet).
Will is very sexist, especially towards Penny.