Killy is number 1. No argument there.
Runners up should definitely include:
The men of the 10th Mountain Division
Les Otten. Whether you like him or hate him, he revolutionized skiing in the the Northeast with his destination resort developments.
Charlie Lord for what he accomplished at Stowe.
Phil and Steve Mahre for getting everyone pumped about the sport in the 80s.
Here's a wildcard:
The Earl of Kandahar
In 1879, an English officer, Frederick Roberts, rescued the besieged garrison of British troops in Kandahar. He was subsequently knighted with the title “Earl of Kandahar.” In 1911, Roberts, who was an avid skier donated a cup to be awarded to the winner of the Kandahar race. Since then, the event has been known as the “Arlberg-Kandahar” race.
There's also a famous trail named after him at Garmisch-Partenkirchen.
The earl is partly responsible for getting the English speaking world charged up about the sport at the turn of the century.