Captain Lock was a clone captain in the Grand Army of the Republic. He served under Eeth Koth, and was the leader of Horn Company.

Captain Lock was born in 32 BBY on the planet Kamino. He was placed into the Alpha-17 Training program, where he developed an individual personality and leadership skills. He participated in the first battle of geonosis at the beginning of the clone wars. In 21 BBY, Lock and horn company were on Eeth Koth’s Venator class star destroyer when it was boarded by General Greivous. Lock was ordered to flee the ship in an escape pod.