Imperial Scout Troopers (also called "Scout Stormtroopers" or "Biker Scouts") are an elite group of Stormtroopers, trained to use high-speed vehicles (normally speeder bikes) to scout and survey areas, locate enemy positions, and on some occasions, infiltrate enemy lines to perform sabotage missions. Scouts operate in groups of 4 called "lancers," each led by a sergeant. They often work in conjunction with other heavy reconnaissance vehicles, such as Imperial AT-ATs.
Scout Troopers made an appearance in Star Wars Episode III: Revenge of the Sith as the Grand Army of the Republic's BARC Troopers. These soldiers were used heavily by the Republic at the Battle of Kashyyyk near the end of the Clone Wars, fighting the Separatist invasion force of the planet. Compared to the BARC Trooper from which they evolved, the Scout Trooper is more advanced.