ST-103 was a Human who served as an Imperial sandtrooper squad leader assigned to a garrison at Mos Eisley on the planet Tatooine during the Galactic Civil War. During ST-103's assignment on Tatooine, the stormtrooper rode a dewback. ST-103 was a sabacc player, and, like other stormtroopers assigned to spaceports such as Mos Eisley, frequented the gaming tables when off-duty. ST-103 wore a full suit of stormtrooper armor and was armed with an E-11 blaster rifle.