Rogue Jedi
Typically a former Jedi, but can just be someone who has been trained as a Jedi and follows the Jedi Code, but who is unaffiliated or even actively opposed to the Jedi Council. Rogue Jedi are considered quite dangerous by the Jedi Council. Rogues are often driven to their rogue status by extreme political and operational differences with the council.
The J'gang is a notorious group of rogues.