Which Traitor Primarchs Are Dead

Is omegon and Alpharius dead?

Both Primarchs met in combat and Alpharius-Omegon was killed. Believing the combat over, for who could ever survive the loss of their Primarch in battle, the Ultramarines were taken by surprise by the remaining elements of the Alpha Legion, when they struck back a day later.

Is lorgar dead?

Lorgar’s enemies in the Covenant saw this as the opportunity they had been waiting for to remove the threat that Lorgar presented to the status quo, declaring him a heretic to the Old Ways. Those of the Covenant who came forward to arrest Lorgar were killed by his followers.