Keller was a clone trooper commander who served under Jedi General Simms, Jedi General Kai Hudorra, and Jedi Commander Noirah Na. He commanded a special unit of clone troopers and Galactic Marines.
Keller on Toola.
At the onset of the Outer Rim Sieges, Keller and his unit were sent to the frigid Rim world of Toola to combat recent Separatist incursions into the area. When Keller and his unit received Order 66 from Supreme Chancellor Palpatine, Keller and his troops moved against their Jedi leaders. They managed to kill General Simms, but Kai Hudorra and Simms' Padawan, Noirah Na managed to get away and flee to Ithaqua Station.
To keep the two Jedi from fleeing a second time, Keller had his men place Ithaqua Station under martial law, forcing strict curfews on its inhabitants. Despite all this, however, the two Jedi managed to elude Keller's patrols and get onto a transport bound for Coruscant at Toola Spaceport.
During the Clone Wars, Keller wore white clone paratrooper armor with blue and brown markings. He was also equipped with two DC-17 blaster pistols, and a DC-15A blaster rifle.
Keller was ranked as number five on StarWars.com's top ten list of clones for 2005. Hasbro released a figure of Commander Keller as part of its range of Dark Horse Comics figure packs. It included the commander and a Galactic Marine apart of his unit.