Mario & Sonic at the Olympic Games[a] is a crossover sports and party game developed by the Sega Sports R&D Department. It was published by Nintendo in Japan and by Sega in other regions, released on the Wii in November 2007 and the Nintendo DS handheld in January 2008. The first official video game of the 2008 Summer Olympic Games, it is licensed by the International Olympic Committee (IOC) through exclusive licensee International Sports Multimedia (ISM), and is the first official crossover game to feature characters from both the Mario and Sonic the Hedgehog series.

Mario & Sonic on the Wii and DS is a collection of twenty-four events based on the Olympic Games. Players assume the role of a Nintendo or Sega character, using the Wii Remote to mimic sports actions such as swinging a paddle. The DS version uses the stylus and button controls. Both games follow rules and regulations of the specific sports. Sega adopted the IOC's mission of promoting a sportsmanship and interest young people in the Olympics by using its characters; following this theme, Nintendo allowed Sega to include Mario with Sonic the Hedgehog, created by Sega as a mascot to rival Mario in the early 1990s.