Key Mini Mario

Key Mini Mario is a type of Mini Mario with a key, which appears in several games in the Mario vs. Donkey Kong series.

Mario vs. Donkey Kong: Minis March Again!
Key Mini Mario first appears in Mario vs. Donkey Kong: Minis March Again!, being introduced in Room 1-Key and appearing in subsequent Key levels. Key Mini Mario appears in levels with a locked door, which must be unlocked by a Key Mini Mario in order for any Minis to enter the door.

Mario vs. Donkey Kong: Mini-Land Mayhem!
Key Mini Mario reappears in Mario vs. Donkey Kong: Mini-Land Mayhem!, where it appears in the eighth course of each attraction, along with a locked Exit Door. It functions identically to its appearance in the previous game.

Mario and Donkey Kong: Minis on the Move
Key Mini Mario reappears in Mario and Donkey Kong: Minis on the Move in levels with a locked goal. Minis other than Mini Mario can also use keys in this game. In Mario's Main Event, a Mini does not have a key at the beginning of a level with a locked goal; instead, it must collect the key within the level, then use it to unlock and enter the goal. In Many Mini Mayhem, one of the Minis in a level with a locked goal spawns with a key; this Mini must reach the goal first in order to unlock it.

Mario vs. Donkey Kong: Tipping Stars
Key Mini Mario reappears in Mario vs. Donkey Kong: Tipping Stars, with the same function as in Mario vs. Donkey Kong: Minis March Again! and Mario vs. Donkey Kong: Mini-Land Mayhem!.