Gally

"Everything started going wrong the minute you showed up. First Ben, then Alby, and now the girl. Everybody saw she recognized you. And I'm betting you know who she is."

- Gally

Gally  is the main antagonist of The Maze Runner and the anti-hero / supporting protagonist of Maze Runner: The Death Cure. He is a Glader and the Keeper of the Builders who did not trust Thomas, thus he becomes his enemy and rival, except in Maze Runner: The Death Cure where he becomes his friend and ally.

He is portrayed by Will Poulter in his first heroic role.

The Maze Runner
Gally arrives in the Glade three years before Thomas arrived, and becomes the Keeper of the Builders.

Three years later, since Thomas arrived, Gally engages him as a runner.

After the Grievers attack some Gladers and partially destroy the Glade, Gally puts the blame on Thomas.

Later, he has Thomas and Teresa Agnes imprisoned. When Gally has Teresa tied and attempts to have Thomas tied, Thomas wakes up and reasons him and the other Gladers about WCKD and the Glade. Gally lets Thomas, Teresa, Newt, Minho, Frypan, Chuck, Winston, and Jeff escape while he decides to stay in the Glade with the other Gladers.

Gally has been stung by a Griever and aims a gun at Thomas. but Minho throws a spear into Gally's heart, killing him. while Gally shoots a bullet into Chuck's heart, killing him.

Maze Runner: The Death Cure
It is revealed that Gally has survived. He teams up with Thomas, Teresa, Newt, Minho, Frypan, Brenda, and Jorge, and the team infiltrates the WCKD headquarters, and manages to crumble WCKD for good.