Johnny Gayle is an American, former Green Beret commander, who specialized in guerrilla warfare.
He was hired for the Death-T theme park at Kaiba Land, which was created to kill Yugi Mutou. Gayle was put on a team with Bob McGuire and "name unknown" to face Yugi and his friends in the first stage of Death-T. Each of them were promised a bounty of ¥10,000 for each opposing player they killed.
Kaiba rigged the game so that the three men on his team have real lasers that cause fatal electric shocks when fired while Yugi and his friends were given toy guns.
When the three mercenaries discussed how they should take out their opponents, Gayle suggested that they leave it to him, as he was the expert in guerrilla warfare. He planned to pursue a surprise attack and finish them in an instant. With the opposition being amateurs, he predicted that they would be scared stiff when he jumped out in front of them. Gayle made his way through the battlefield, while back at their starting post, McGuire accused him of showing off and wanting the bounty all to himself.
As Gayle crawled through the battlefield, Katsuya Jonouchi suddenly appeared standing on the wall above him. Gayle was surprised that Jonouchi came up with an attack more surprising than his. Being the one with weapon training, Gayle was able to aim his gun much quicker. However Jonouchi opted not to use his weapon and kicked Gayle in the face, eliminating him from the game.