Super Mario Bros. 2, known in Japan as Super Mario USA, and also known as Super Mario 2 in Super Mario All-Stars and Super Mario Advance, is the second game in the Super Mario series outside Japan. It is a 2D platforming game originally released for the Nintendo Entertainment System in North America on October 9, 1988. In the years that followed, it has been ported to many other systems, including a release on the Wii's Virtual Console in 2007, the Nintendo 3DS's Virtual Console in 2012, and the Wii U's Virtual Console in 2013. As a result of Japan already having a Super Mario Bros. 2 (known in English as Super Mario Bros.: The Lost Levels and Super Mario Bros. for Super Players), the game did not make its debut in the country until after the release of Super Mario World, on September 14, 1992, making it Japan's fifth installment of the series.

One of the central game mechanics that differentiates Super Mario Bros. 2 from other Super Mario games is that players can select four characters – Mario, Luigi, Toad, or Princess Toadstool – and each of these characters have their unique gameplay mechanics, offering advantages and disadvantages in their stats. Another distinction is that players cannot defeat enemies by stomping on them: players need to either toss items at enemies or pick up and toss enemies at each other to defeat them.

Super Mario Bros. 2 came about after Nintendo of America deemed Super Mario Bros.: The Lost Levels too difficult for Western audiences, which led Nintendo to redevelop the Family Computer Disk System game Yume Kōjō: Doki Doki Panic into a Super Mario Bros. game for the international release. After its release, the game became a commercial success, and eventually the game became well received enough that it was also released in Japan. After performing well both critically and commercially, Super Mario Bros. 2 has been re-released as one of the four games featured in Super Mario All-Stars, and as well as having its own remake in Super Mario Advance. Many enemies first introduced in Super Mario Bros. 2 have become common recurring enemies in the Mario franchise, like Bob-Ombs, Pokeys, Shyguys, and more, while the gameplay mechanic of picking up various items and tossing them has been reused in several later games.