"The Mega Man X (Rockman X in Japan) series is the second Mega Man franchise released by Capcom. It debuted December 17, 1993 in Japan (February 1994 in North America) on the Super NES/Super Famicom. It is the first continuation in plot of the series, preceded by the classic Mega Man series. The first six games in the series are currently available in the anthology collection Mega Man X Collection.
Capcom released Mega Man X for the Super NES to give a new image to the Mega Man game series. There is a total of 11 games in the Mega Man X series: Mega Man X, X2, and X3 on the Super NES (with ports of X and X3 to the PC, and a Japan/Europe only port of X3 to the PlayStation and Sega Saturn), Mega Man X4, X5, and X6 on the PlayStation (X4 also being on the Sega Saturn, as well as X4 and X5 being ported to the PC), Mega Man X7 and X8 on the PlayStation 2 (X7, X8 also being on the PC in Korea, Japan and Europe), the RPG Mega Man X: Command Mission on the Nintendo GameCube and PlayStation 2, and Mega Man Xtreme and Xtreme 2 (Rockman X: CyberMission and Rockman X2: Soul Eraser in Japan) on the Game Boy Color. The original Mega Man X was remade on the PlayStation Portable as Mega Man Maverick Hunter X."
Source: Wikipedia, "Mega_Man_X", available under the CC-BY-SA License.