Best identified by their long white breather mask, the Snowtrooper is a specialist Stormtrooper for arctic conditions. Snowtroopers were used extensively in the Battle of Hoth.
Snowtroopers were introduced in version 1.0 of the game.
Although they do not show a number on their description for possible scenes, Snowtroopers unlock two: at Scoop Of Hoth and Imperial Museum. They may also unlock the Tractor Beam. (These were missing in version 1.3, but were restored in 1.4.)