William "Bill" Sellier is an American still photographer, US Army veteran, and tactical authority. He spent his early years immersed in independent filmmaking. When he was just a teenager, he graduated from the prestigious School of Modern Photography and quickly established himself as a trusted set photographer in the film industry. He captured behind-the-scenes and promotional imagery for notable films of the era. In the mid-1980s, Sellier transitioned from cinema to a highly decorated career in public service and tactical defense. He served as a Deputy and SWAT Commander for the Wasatch County Sheriff's Office in Utah. As a commercial instrument rated pilot, he flew fire reconnaissance for the U.S. Forest Service and served in the military as a flight combat medic for the 1250th Air Ambulance. He was a Nuclear, Biological, and Chemical Specialist for the elite 19th Special Forces Group (Airborne) and later commanded soldiers as a Quick Reactionary Force Sergeant within the historic 25th Infantry Division while assigned to the 71st Chemical Company. Following his military commitment, Sellier worked as a civilian defense contractor and was an industry authority on Tactical Air Navigation (TACAN) systems.