Mega Man X5 is the fifth main game in the Mega Man X series by Capcom. It was released in 2000 for the PlayStation, three years after Mega Man X4, and in 2002 for PC. This was re-released on January 10, 2006 as part of the Mega Man X Collection for the GameCube and PlayStation 2.

An indeterminate amount of time after the events of Mega Man X4, a new plot to destroy the Maverick Hunters is hatched by Sigma, who has been revived again (as in X4, it is unknown who revived him or how). Sigma, after conducting research on the origin and design of Zero, decides to discover how to unlock Zero's true power, hopefully destroying X in the process. Sigma attacks the Maverick Hunters directly, intending to lose. When he does, he spreads a Maverick virus across the Earth, throwing it into chaos. Meanwhile, a Reploid mercenary named Dynamo is hired by Sigma to make the Space Colony Eurasia collide with Earth. The Hunters have only 16 hours to avoid collision.

X5 was developed by a different team than X4, and this is very evident in the style of gameplay. The most prominent difference in this iteration is the time limit of 16 hours, until the space station Eurasia crashes into Earth. If the crash is not prevented, this does not end the game - it merely changes the course of the story. Every time the player enters a stage, one hour is expended. Due to the nature of the storyline, there are multiple endings to the game. Which ending is seen depends on such factors as whether or not the crash of Eurasia is prevented, and whether X or Zero is used to defeat the last boss.