Commissioned after the end of the Clone Wars by the Emperor, "Knightwatch" was the codename given to a select group of Clone veterans assembled for the purpose of hunting down rogue Jedi, Clone deserters, and their supporters. Despite serving a similar purpose, the group operated independently of Vader's 501st.
Knightwatch exists and operates somewhere amongst the cracks between the infrastructure of the ISB, Imperial Intelligence, and the Imperial Military. The group enjoys a good deal of free reign in their operations, operating on and answering to the Emperor's interests.
Moff Rathos spent the Clone Wars embedded in the Separatist forces as a spy, with his main mission being the observation of the planning of the Separatist super-weapon that would become the Death Star.
Rathos bought credibility for his cover role by providing Republic intel on the position of Clone forces. These leaks were calculate by the Chancellor and Senate to result in somewhat significant Clone causalities but not disrupt overall Republic operations.
Now promoted to Moff and assigned to Knightwatch, Rathos oversees the group and acts as a direct liaison for the Emperor and his interests. Though ruthless and self-serving, he retains the Emperor's favor so long as those interests remain inline with the Empire's.
Specialist Trakker - Head
Grand Moff Trachta - Torso, Belt
Captain Needa - Legs
Cade Skywalker - Coat
Baron Papanoida - Arms