A Breen primarch responsible for the death of Rayner's family, who sought to claim Primarch Ruhn's forces and the Progenitors' technology.
Tahal is a Breen primarch introduced in Lagrange Point. After learning that Primarch Ruhn has been killed by Moll, she sets out to claim Ruhn's forces for herself, putting a second Breen fleet on course for the Progenitors' technology.
Tahal is personally responsible for the death of Rayner's family during the Breen occupation he survived. Saru volunteers to intercept her forces in hopes of stalling them, giving Michael Burnham time to retrieve the technology from Moll's dreadnought.
In Life, Itself, Saru convinces Tahal to stay away, although she sends a scout ship to investigate. The Discovery crew uses its spore-based propulsion to send both the Breen dreadnought and Tahal's scout ship to the edge of the galaxy, keeping the Progenitors' technology out of Breen hands.