Gregg was a human male Striker Titan who briefly fought in the Europa Incident. After following Arxus Essal to Europa, he offered to help both Arxus and the bounty hunter Stalker with infiltrating one of the House of Storms strongholds. However, due to sloppiness, Gregg was caught by Fallen Guards and killed, his Ghost rended of Light. As not many Fallen are known to be able to destroy Ghosts, it was most likely Rhall who sealed Gregg's fate. Arxus and Stalker did not notice the unfortunate Guardian's disappearance, and simply believed that the Guardian had left the moon.