A Breen primarch who sought the Progenitors' technology and declared war on the Federation over his nephew L'ak.
Primarch Ruhn was the leader of a powerful Breen faction in the 32nd century. He came to Federation headquarters to claim his nephew L'ak, a descendant of the former Breen emperor, intending to use him to legitimize his own claim to the throne. When L'ak died in Federation custody, Ruhn declared war and took L'ak's partner Moll with him.
Ruhn then raced Discovery for the Progenitors' technology. Michael Burnham traded him the completed map for a promise to spare the Eternal Gallery and Archive, but he chose to destroy it anyway, and Moll exploited his followers' discontent to kill him and take command.