The main governing organization of the Galactic Empire was the Supreme Tribunal. Cos Dashit, under the leadership of the Emperor, was officially known as the Consul to the Supreme Tribunal. Its composition numbered at a minimum of five individuals.
Vantos Coll, Darth Vader, and, it is believed, Crispin Hoedaack were also individual members of the Tribunal. Following Hoedaack's successful acquisition of the Aquilaean system, these three created a secret group with the intention of seizing control of the Empire.
The Great Families were formerly represented by the Tribunal's members, but the cabal had already removed them from their positions of authority.
The Supreme Tribunal, in the initial draft, occupied a role comparable to that of the Imperial Senate in subsequent iterations. The eventual dismantling of the Senate appears to be a result of the removal of the Great Families. The command staff meeting on the Death Star evolved from the various members and their discussions.