Toland, the Shattered

Toland, the Shattered was a warlock who studied the Darkness and eventually went mad, leaving the City in Exile. He was part of the six Guardians who delved into the Hellmouth in search of Crota. Considering only Eris came back alive, he is assumed to be dead.

Toland's studies lead him to conclude that the Darkness was the evolutionary endpoint of the universe, and that its campaign of destruction was to ensure that nothing could ever rise up to challenge it. Toland even claimed to be able to commune with the Darkness, with an increasingly morbid curiosity in Hive rituals.