CT-3423 was a clone trooper who served in the Grand Army of the Republic during the Clone Wars. He was part of the 91st Reconnaissance Corps under Clone Commander CC-8826 during the Siege of Saleucami in 19 BBY. Later, CT-3423 and CC-8826 went on a speeder patrol of Saleucami with Jedi Master Stass Allie. Through his helmet comlink, CC-8826 received Order 66, which branded the Jedi as traitors to the Republic, and he informed CT-3423 of the order. CT-3423 and CC-8826 then utilized their BARC speeders' blaster cannons to fire on Allie's speeder, destroying it and killing her.