Harbinger

Harbinger was the leader of the Reapers, a powerful legion of Sentinel warships that were on a constant cycle of the extinction of life on a Universal scale every few million years. The leader of the Reapers was assigned by The Child, and it was to be Harbinger, whom displayed the most experience and intelligence out of his brothers.

The Reapers continued their voracious cycle for eons, keeping the universe's power levels in check and disabling any empire from overgrowing and becoming majorly powerful. However, this balance was cut short due to the sneaky machinations of Morgoth, who caused a glitch in their database and reschedule a cycle due in the midst of the Pike Lore back another few million years.

However, Harbinger noticed the virus and quickly snuffed it out, but the Reapers were still held back 20 years from their original goal.

When the Reapers were finally activated for their goal of extinction, they encountered many space empires and civilisations that posed a threat to them. To this end they employed the Drone Species of the Collectors to begin a military conquest of genocide upon the more powerful empires and republics that opposed their aims.

Harbinger and his Reapers would reach Coruscant at a pivotal time, Morgoth's corruption had turned the land into the Dark Plains, and it was the final battle between the Morgothian armies and Pike's forces.

Harbinger, remembering Morgoth and being driven by vengeance, attacked the dark god, only for his entire species to be incinerated by Morgoth in a single try... Jesus

The Reapers were long thought dead, but Harbinger barely clinged onto life in a desolate part of the Galaxy, surviving in his Collector body, Harbinger rethought his nihilistic mission and left his old ways, joining the 9th United Republic.