Keyzer

"He looks like a pushover... Too bad he's not an enemy! I'm out here risking my life and he just sleeps all day! Hey! Keyzer! You'd better wake up and smell the coffee or I'm to smack you one real nice!!"

- Wario

Keyzer, or Key Bird, is a small ghost-like creature with a key for a nose found in the Game Boy Advance game Wario Land 4. If collected, it will follow Wario until he exits the level. It will then unlock the sealed door that leads to the next level for Wario, and will disappear once it does so. The Keyzer can always be seen sleeping before Wario obtains it, and looks upon Wario with distaste when Wario wakes it up. He appears in all eighteen levels. If Wario returns to a level where a Keyzer has already been collected, it won't be found again. In the level Crescent Moon Village, a ghost called Yūrei shows an interest in Keyzer, and tries to steal him from Wario because Yūrei seems a bit lonely. Yūrei won't give up his prize easily so Wario must hunt down his stolen key, thus wasting valuable time.

In the game's instruction booklet, Wario states that Keyzer looks like a pushover and he could easily take him down.