(Unique game aspects not part of story canon)
Wesker's Monster is a monkey-based enemy design that was ultimately rejected during the development of the Nintendo 64 Resident Evil Zero title. It was presented in a 2015 "Developer Diary" video during the production of the GameCube game's 2016 re-release.
The purpose of this creature was to serve as a means of Albert Wesker killing off the S.T.A.R.S. Bravo Team. Ultimately, Wesker was dropped as the game's main villain in favour of the "mysterious young man" due to problems revolving how to link Zero to the first game, thus rendering the use of this creature moot. Wesker's Monster was later re-designed as the Eliminator, which made it to the GameCube release.