The Danger Room is a fictional training facility appearing in American comic books published by Marvel Comics. It first appeared in The X-Men #1 and was created by Stan Lee and Jack Kirby. The facility is depicted as built for the X-Men as part of the various incarnations of the X-Mansion. Its primary purpose is to train the X-Men, initially using traps, projectile firing devices, flamethrowers, and mechanical dangers such as presses and collapsing walls. These were replaced by holographics, when the Danger Room was rebuilt using Shi'ar technology. It gained sentience in Astonishing X-Men as Danger.

X-Mansion and Xavier Institute are the common names for a mansion and research institute appearing in American comic books published by Marvel Comics. The mansion is depicted as the private estate of Charles Francis Xavier, a character in X-Men comics. It serves as the base of operations and training site of the X-Men. It is also the location of an accredited private school for mutant children, teenagers, and sometimes older aged mutants, the Xavier Institute for Higher Learning, formerly the Xavier School for Gifted Youngsters. The X-Mansion is also the worldwide headquarters of the X-Corporation.