The Cult of Galvatron is a religious offshoot of the Cult of Unicron. The Cult of Galvatron wishes to sacrifice Megatron and use his energon in dark resurrection rituals. The cult gained attention when it started targeting the Decepticon Sweeps.
In 2014 the Cult came to Earth to use its energy resources to build a giant replica of Galvatron to use for their own occult purposes. They found a mysterious mountain with energy disruption properties and used it as their base.
In June of that year Sunstorm and Windshear went undercover, pretending to join the cult.
By July the cult was ready to unleash their Giant Galvatron onto the Decepticons. Megatron and Onslaught led the response, and the cult was taken by surprise when new recruits Sunstorm and Windshear crossed sides and joined the attack against them. Obsidian was killed, and most of the other cultists were slaughtered. The few survivors were gathered up by Windshear, and, against the orders of Megatron, released on Cybertron.