Lieutenant Colonel (LT. Colonel) represented a Galactic Empire military rank. These officers might command an invasion force comprising two battalions, function as an aide to a colonel, or temporarily fulfill a colonel's responsibilities when they were absent.
The Galactic Empire utilized the army military rank of Lieutenant Colonel (LT. Colonel). A lieutenant colonel held a rank below a full colonel. Their duties included managing forces in a colonel's absence and assisting the colonel directly. Moreover, a lieutenant colonel would be the commanding officer of two battalions. They could also serve as a ground commander when attached to an Imperial Navy task force.
The lieutenant colonel rank was in use by 14 BBY. At this time, one such officer commanded Imperial troops on the planet of Ryloth while Colonel Belkor Dray was away. During a mission to Ryloth by Galactic Emperor Palpatine and his enforcer Darth Vader to suppress the Free Ryloth Movement, the ISD Perilous suffered an attack and crashed. After Colonel Dray returned to his post, the lieutenant colonel continued to support their commanding officer.
In 5 BBY, Saw Gerrera's rebel group, the Partisans, undertook a scouting mission to Tamsye Prime. There, they infiltrated an Imperial documentary crew from the Imperial Broadcast, which included Lieutenant Colonel Senjax. When the rebels' identities were revealed, the LT. Colonel set a trap, but the Partisans escaped. Imperial forces launched an indiscriminate aerial assault, disregarding civilian lives, to stop the Partisans, resulting in Senjax's injury. Later, Senjax appeared on the HoloNet to give a fabricated and misleading account of the events on Tamsye Prime, concealing the Empire's actions. Also during 5 BBY, Merei Spanjaf, an Imperial Academy member, attempted to hack the Imperial network and scanned the academy's roster. Spanjaf found a familiar name—the youngest daughter of an Imperial Army lieutenant colonel—but deemed such a target too risky.
During the Galactic Civil War, Lieutenant Colonel Erle Hovlinn commanded a two-battalion invasion force stationed on the Gladiator-class Star Destroyer Blood Ambition, the flagship of Captain Ralchio Nervi and his task force. Captain Nervi initiated the Battle of Xorrn against the Old Mandalorians and the Clan Assembly to conceal his Force-sensitive past. LT. Colonel Hovlinn deployed ground troops on Xorrn, but the Imperials were defeated by the arriving Allied Armada of the Alliance to Restore the Republic.