In the Babylon 5 fictional universe, the Grey Council is the governing body of the Minbari Federation. Its members carry the title satai. Delenn, one of the main characters of Babylon 5, is a member of the Grey Council.
Founded by Valen 1,000 years before the Shadow War, the Grey Council comprised three representatives from each of the three castes - Worker, Warrior, and Religious - for a total of nine individuals. From time to time, the council had an additional member, a leader who served as a guide for the council. It is not known if this person had a vote or not; nor is the scope of their authority known. Dukhat, who served in this role, indicated that he could override the Council, but it is not clear if this power arose from his personal authority or qua the leader of the council.
For about 1,000 years, the Grey Council ruled over nearly every aspect of Minbari life, choosing its own membership and meeting in space aboard a Sharlin class Minbari cruiser. Its name is interconnected with its purpose through a sacrament repeated by its members: "I am Grey. I stand between the candle and the star. We are Grey. We stand between the darkness and the light."
The title of Satai is used exclusively for members of the council. Ambassador Delenn is satai, but wishes her title to remain secret on the Babylon 5 station (the reasons for this are given to the viewers very early in the plot, in the movie Babylon 5: In the Beginning). Commander Jeffrey Sinclair first learns about Delenn's title (and, inferentially, membership of the council) in the second episode of season 1, Soul Hunter.
During a period concluding in the mid 2240's, the Grey Council was led by Dukhat, until his death during a disastrous first contact with humans. The Council's cruiser encountered a flotilla of Earth Alliance ships, and approached with gun ports open, a gesture of respect in the tradition of the Minbari Warrior Caste. The earth ships (under command of a captain with a reputation for recklessness) misinterpreted the gesture as prelude to an attack and attacked the Council's ship. Dukhat suffered fatal injuries in the attack. Voting 5-4 - the fifth vote provided by a grief-stricken Delenn - The Council declared war on humanity. Over the next two years, the Minbari overcame tenacious resistance and routed Earth forces.