Donkey Kong Jr. is a 1982 arcade platform game that was released by Nintendo. It is the sequel to Donkey Kong, but with the roles reversed compared to its predecessor: Mario (previously named "Jumpman") is now the villain and Donkey Kong Jr. is trying to rescue his father. It first released in arcades and, over the course of the decade, was released for a variety of home platforms. The game's title is written out as Donkey Kong Junior in the North American arcade version and various conversions to non-Nintendo systems.

The game was principally designed by Shigeru Miyamoto and his coworker and the company's chief engineer Gunpei Yokoi. Miyamoto also created the graphics for the title along with Yoshio Sakamoto. As with its predecessor, the music for the game was composed by Yukio Kaneoka.