Chaos Lieutenant

From Lexicanum

A Chaos Lieutenant is a later 3rd Edition rank, second to Chaos Lord. They could be given psychic powers and would become a Chaos Sorcerer, though this path doesn't follow the new route for Chaos Sorcerers, being originally Librarians rather than direct commanders. They were often seen as the right-hand men to Chaos Lords, though would often try to benefit from any unfortunate events which could lead to their own increase in power.¹

Sources

• ¹:Codex: Chaos Space Marines (3rd Edition, 2nd Codex)