Gambit is a fictional character appearing in American comic books published by Marvel Comics, commonly in association with the X-Men. The character was created by writer Chris Claremont and artist Jim Lee. Drawn by artist Mike Collins, Gambit made his first appearances in The Uncanny X-Men Annual #14 and The Uncanny X-Men #266. Gambit belongs to a subspecies of humans called mutants, who are born with superhuman abilities. Gambit has the ability to mentally create, control, and manipulate pure kinetic energy to his desire. He is also incredibly knowledgeable and skilled in card throwing, hand-to-hand combat, and the use of a bō staff. Gambit is known to charge playing cards and other objects with kinetic energy, using them as explosive projectiles.

Mister Sinister is a supervillain appearing in American comic books published by Marvel Comics. Created by writer Chris Claremont, the character was first mentioned as the employer behind the team of assassins known as the Marauders in The Uncanny X-Men #212, and later seen in silhouette in The Uncanny X-Men #213, with both issues serving as chapters of the 1986 "Mutant Massacre" crossover. Mr. Sinister then made his first full appearance in The Uncanny X-Men #221. His appearance was designed by artist Marc Silvestri.