Those who piloted All Terrain Armored Cargo Transports were Galactic Empire army or navy personnel known as AT-ACT drivers. Their attire consisted of white Imperial tank pilot armor, with some breastplates displaying markings akin to those on Imperial combat assault tank commander armor. Completing their uniform was a white coastal defender stormtrooper helmet, featuring grey and red designs, notably a red Imperial crest on the pilot's helmet. For personal defense, these drivers were equipped with either E-11 or E-22 reciprocating double-barreled blaster rifles. Although they existed, dedicated AT-ACT driver units were not established because the AT-ACT was not considered a primary combat vehicle.
During the Galactic Civil War that pitted the Empire against the Rebel Alliance, AT-ACT drivers were stationed at the Imperial security complex situated on the planet Scarif. In 1 BBY, the Rebel squad "Rogue One" infiltrated this Imperial installation, aiming to seize the Death Star plans, an action that triggered the Battle of Scarif. During this conflict, AT-ACT drivers employed their walkers to engage the Rebel ground troops, initially achieving success and pushing them back. However, the arrival of support from the Alliance Fleet quickly turned the tide, with Blue Squadron's T-65 X-wing starfighters and UT-60D U-wing starfighter/support craft swiftly neutralizing the walkers. Subsequently, the Death Star, under the command of Grand Moff Wilhuff Tarkin, obliterated the security complex.
The concept and design of AT-ACT drivers were developed for the 2016 film Rogue One: A Star Wars Story. However, the character's debut occurred earlier as a 3-3/4" action figure in Hasbro's Rogue One toy line, included with the Rapid Fire Imperial AT-ACT toy (along with figures representing Jyn Erso and C2-B5) which was released in November of 2016. A notable error appeared on the Rapid Fire Imperial AT-ACT's packaging artwork, which incorrectly displayed the AT-ACT driver's helmet bearing the red symbol typically found on the shoretrooper helmet, as opposed to the correct red Imperial crest present on the actual figure's helmet and in the film itself.
Despite the availability of AT-ACT driver action figures, the reference book Star Wars: Rogue One: The Ultimate Visual Guide, penned by Pablo Hidalgo and released concurrently with the film, contained a statement asserting that no specialized corps of pilots existed for the AT-ACT, a claim made despite the presence of an image depicting an AT-ACT driver helmet directly adjacent to the text.