Commander Keller, a clone trooper commander, served under the command of Jedi General Simms, Jedi General Kai Hudorra, and Jedi Commander Noirah Na. He was in charge of a special unit composed of both clone troopers and Galactic Marines.
As the Outer Rim Sieges began, Keller and his unit were dispatched to Toola, a cold world located in the Rim, to fight against the recent Separatist activity in that sector. After receiving Order 66 from Supreme Chancellor Palpatine, Keller and his men turned on their Jedi superiors. While they succeeded in eliminating General Simms, Kai Hudorra and Noirah Na, Simms' Padawan, were able to escape, making their way to Ithaqua Station.
To prevent another escape by the two Jedi, Keller placed Ithaqua Station under martial law, enforcing strict curfews for all residents. However, the two Jedi were still able to evade Keller's patrols and board a transport headed to Coruscant from Toola Spaceport.
During the Clone Wars, Keller's armor consisted of white clone paratrooper armor featuring blue and brown designs. His standard armament included a DC-15A blaster rifle along with two DC-17 blaster pistols.
In 2005, Keller was ranked fifth in StarWars.com's top ten list of clones. A Commander Keller action figure was released by Hasbro as part of their Dark Horse Comics figure sets. The pack included the commander alongside a Galactic Marine from his command.