Brian Ellis was a 24th century Human man. Ellis was a member of Starfleet, serving as a counselor in the 2380s, a specialist in post-traumatic stress. As of 2381, he was assigned to Starbase 22.
Following the Borg Invasion of 2381, Ellis was extremely busy counselling survivors of the conflict. On stardate 58332.2, Ellis met with Ensign Dmitri Nakahara of the USS Hood, who confessed to killing seven former Borg drones liberated by the Caeliar. Ellis was shaken by this story, and nearly decided not to report it to Nakahara's superiors.
Among the other individuals Ellis counselled following the invasion were Byron Fantomos, Alhan Jago, Kara na Miin, Thaddeus Samson, Seareg, Tando, Valak, and Yoralig. (ST novel: A Singular Destiny)