Starfleet admiral and psychologist who oversaw Gabriel Lorca during the Klingon War and later gave her life to save the USS Enterprise.
Katrina Cornwell, played by Jayne Brook, is a Starfleet admiral in the 2250s whose background lies in psychology and mental health. She serves as the direct superior of Gabriel Lorca aboard the USS Discovery, and the two once shared a romantic relationship.
During the Klingon War, Cornwell grows worried about Lorca's state of mind and considers relieving him of command. Soon after, she takes Sarek's place as a peace envoy and is captured by the Klingons, who hold her aboard the Ship of the Dead. In captivity she forms an uneasy rapport with L'Rell, and her training helps pull Ash Tyler out of a traumatic flashback before Michael Burnham and Tyler rescue her. Back in Starfleet, she helps steer the endgame of the war and later works with Discovery and the Enterprise against Section 31's rogue intelligence, Control.
Cornwell's arc ends during the battle against Control, when she sacrifices herself to protect the Enterprise. She stands for the conscience of a Starfleet leadership under heavy wartime strain.