Barracks D5 was a military building located in Timira City on Kamino, a planet. The Galactic Empire's military constructed this barracks. The clone of Galen Marek, who was the deceased Sith apprentice of Sith Lord Darth Vader, known as Starkiller, made his escape from the city in 1 BBY.
As the escape occurred, a stormtrooper indicated that Starkiller's location was in the vicinity of Barracks D5, during the Imperial forces' attempts to capture the clone.
The LucasArts video game Star Wars: The Force Unleashed II, which came out in 2010, was the first time Barracks D5 was referenced. Depending on the playthrough, the stormtrooper who reports Starkiller's location may or may not mention Barracks D5.