Which character is held captive by Mario in Donkey Kong Jr.?

The character held captive by Mario in Donkey Kong Jr. is Donkey Kong.

The game’s story deliberately reverses the setup of the original Donkey Kong. In the 1981 arcade game, Donkey Kong is the antagonist who holds Pauline captive while Mario climbs the construction site to save her. In Donkey Kong Jr., Mario has defeated Donkey Kong, placed him in a cage, and taken him to a hideout.

Donkey Kong’s son, Donkey Kong Jr., becomes the playable hero. He must navigate vines, chains, and platforms, avoid enemies, and collect keys connected to his father’s cage. The first three stages involve reaching a key beside the cage; the final stage requires pushing six keys into locks to complete the rescue.

This early arcade story differs from the later Donkey Kong Country continuity, where Donkey Kong is generally portrayed as a heroic protagonist and Mario is not his captor. It also predates characters such as Diddy Kong and King K. Rool, so neither is involved in the original rescue plot. Pauline belongs to the first game’s story rather than the captive role in Donkey Kong Jr.