The recent leak surrounding Rainbow Six Siege suggests that Master Chief, the main character from Xbox's Halo series, may be introduced to the game in the near future. It's not surprising, given Ubisoft's track record of incorporating characters from various games into their multiplayer first-person shooter. Previous collaborations have featured characters from WWE, NieR, Yakuza: Like a Dragon, Resident Evil, and more.
According to what Klobrille shared on Twitter/X, Master Chief is coming to Rainbow Six Siege as an Elite Skin Bundle for Sledge, with themed cosmetics and an MVP animation to boot. However, Ubisoft has not made any official announcement for the upcoming Sledge's Elite Skin.
While the Rainbow Six Siege Y8S3 update (Operation Heavy Mettle) has recently become available on the test servers (with the official release date set for August 29), it's important to note that if the leak holds true, players might need to wait until the Y8S4 update or later for the Halo's Master Chief collaboration.