Master of Orion II: Battle at Antares (MOO2) is a turn-based strategy game released in 1996, developed by Simtex and designed by Steve Barcia and Ken Burd. It is the first sequel to Master of Orion. The Windows 95 and MS-DOS version of the game was published by Microprose in 1996, while the Apple Macintosh version was published a year later by MacSoft. Master of Orion II won the Origins Award for Best Fantasy or Science Fiction Computer Game of 1996, and most reviews by critics and players were very favorable.

The game is still played online, and one group of fans has developed a patch, which fixes some bugs and adds more game set-up options, and a few mods which adjust the game balance.