Gargantum

Gargantum was a Jiralhanae Chieftain and Ship Master of the Covenant Frigate Twilight Compunction.

Installation 05
He was aboard his ship during the Battle of Installation 05 and when the Civil War of the Covenant broke out, he took control of several other Jiralhanae-held ships in the Second Fleet of Homogenous Clarity and brought them to attack the Sangheili ships.

His ship, along with the Tenebrous, tried to attack the Sangheili ship, Incorruptible, but the attack was stopped when the Tenebrous was destroyed by the Incorruptible and the Twilight Compunction was attacked and damaged by the Sangheili Carrier Lawgiver.

The Chase
Gargantum's ship, along with the Reverant and another frigate, followed the Incorruptible as it tried to escape. When the ship Bloodied Spirit dropped out of Slipspace nearby, Gargantum hailed it and discovered it was controlled by a team of SPARTAN-II Commandos.

He sent one frigate to attack it, but while his forces were divided, the Revenant was destroyed by the Incorruptible. Gargantum then took his two remaining ships to pursue the Bloodied Spirit.

Trivia

 * Interestingly his name does not contain the "us" suffix that signifies adulthood. This is most likely just a error on the part of the editor.