Thomas is a FINDER and one of the creators of THE SPACE SATION along with Teresa Agnes. He is the main protagonist of the series, named after Thomas Edison. Thomas's real name before being taken by WICKED
In The Kill Order, Thomas undergoes an operation for the Swipe so he can be sent into the Maze with the other Gladers. Through the entire operation, Teresa is by his side, scared about what will happen to her and Thomas, but calm, believing that WICKED will find a cure for the Flare for the sake of humanity. Thomas is then put into the Box and lifted into the Maze.
In the epilogue, it is revealed that Thomas was named after Thomas Edison because a WICKED agent pointed out a hanging light bulb in his mother's house, saying, "You know who made that, right? We should call this one Thomas."
In Lost In Space , Thomas wakes up in a lift with no memory except for his name. When the lift opens, he is surrounded by other boys who also have no memory except their names. This place is called the Glade. The Glade is surrounded by a gigantic Maze with walls moving and changing every single night. Every morning, the Doors to the Maze open, and every night they close. The Gladers do not want to be stuck in the Maze when the walls close, for they could be "stung" by the slug-like monsters called Grievers that lurk in the Maze. As Thomas adjusts to life in the Glade, he befriends a younger boy named Chuck.
When Thomas discovers that Runners go into the Maze to try to find a way out, he feels that he should be a Runner. Then, when a girl comes up in the Box, Alby and Newt call Thomas over because they feel that the girl and Thomas have a connection. Thomas denies having any memory of her, but he does feel like he knows her. The girl is in a coma and the Med-jacks take care of her.
In the morning, Alby and Minho go into the Maze to inspect an apparently dead Griever Minho found. At night, just as the walls begin to close, Thomas sees Minho dragging an unconscious Alby towards the Glade; the Griever had been playing dead and Alby had been stung. Thomas wants to go and help, and, ignoring the rules, dashes into the Maze right before the walls close. Minho is angry at Thomas for doing something so pointless, as he believes all three of them will die. At the sound of Grievers in the distance, Minho leaves Alby and Thomas and runs off, believing their chances will be better if they split up. Thomas drags Alby to the wall and starts tying him to the vines, working him higher and higher above the ground. When a Griever finally appears, Thomas lures it away from Alby by running deeper into the Maze. When he finds himself surrounded by several Grievers, he runs away, and then, turning around, he leaps over the one chasing him before it can slow its momentum.
He later meets up with Minho and the Grievers chase them. Minho tells Thomas to follow him and they go to the Cliff. The Grievers are still chasing them, but Minho has an idea based on what Thomas did with his run-and-jump maneuver. They both stand at the edge of the Cliff, and when the Grievers charge at them, they jump away and the Grievers fall over the edge. In the Cliff, there is a Griever Hole, where things in the hole disappear.
In the morning, Thomas takes Alby off of the wall vines. Thomas, Alby, and Minho are the first people to survive in the Maze for a whole night. Alby is given an antidote for his Griever sting. When Thomas visits him, Alby tries to tell Thomas what he saw during his Changing. However, Alby grabs his own neck and starts choking himself. Thomas calls for Newt, and together they get Alby to stop hurting himself. Newt says that Alby is crazy, even though Alby says that he was being controlled and he didn't know what he was doing.
When Thomas visits the girl, she speaks in his head. Thomas is frightened and in denial about this at first. He learns that her name is Teresa. Teresa tells him telepathically that she triggered "the Ending." Thomas does not know what this means, but soon the walls do not close and bad things begin to happen.
When Teresa is fully recovered, she rushes to Thomas. They talk and begin to form a bond, with Thomas definitely having a crush on her. They also realize that they must have known each other before coming to the Maze.
With the Walls no longer closing, Grievers begin to enter the Glade each night, taking one kid at a time. Thomas and Teresa eventually figure out a code to the Maze. Thomas gets stung purposely by a Griever so he can remember his life before the Maze. He learns that there is only one way of escape: through the Griever Hole. The Gladers make it through the Griever Hole, losing half of their number, including Alby. They are greeted by someone who works for WICKED and Gally. Gally takes a knife and throws it at Thomas, but Chuck takes the hit by jumping in front of Thomas. Thomas is broken by this, going berserk and attacking Gally until he is pulled away by his friends. Then a rescue team comes in and seemingly kills the WICKED members, rescuing the Gladers.