The All Terrain Open Transport (AT-OT) was a walking troop carrier used by the Grand Army of the Republic during the Clone Wars.
As an armored vehicle, the AT-OT differed from the other walkers in Kuat Drive Yards's AT-series, as it was not designed for combat. Instead, it was used to reinforce armies behind friendly lines as a cargo walker.
Although these eight-legged walkers were well-armored and equipped with four laser cannons for defense, their open tops made them extremely vulnerable to attacks from above. AT-OT walkers had enough seats for at least 34 clone troopers, but they could carry more troops if required, thanks to the open-bed design. The vehicle's defenses included two forward cannons and two tail cannons. The AT-OT was not used for attack, it was mainly used for carrying a vast amount of clone troopers onto the battlefield.
With the open top design making transport of troops a risky endeavor, the personnel walker was commonly used throughout the Clone Wars far from the front lines, only traveling far enough to deposit troops at the outer perimeters of battles. They were used to good effect in heavily forested terrain, where cover was relatively easy.
The AT-OT walkers participated in the Outer Rim Sieges, most notably in the Battle of Felucia, where they carried troops through the battlefield and toward crucial water treatment facilities, in an attempt to stop contaminated water from being released into Felucia's planetary water supply by the Separatist leader, Shu Mai.
During the Galactic Civil War, a similar open-top cargo walker, derived from the AT-TE design, served the Empire.