Mr X
Mr X (also written as Mr. X or MRX) was a pseudonym used by a griefing "cult" community on the Cheesebuild map. The accounts used the imagery of Mr X, the farmer from the show Shaun The Sheep as their group banner. It was believed to be ran by DenshiVideo, a Kiwi Farms user & Scratch YouTuber who surrendered a few weeks after the raiding incident.
The accounts calling themselves "Mr X" claimed to be from a Discord server known as the "Mr X Barber Cult" also known simply as the "Denshi Cult". The group has joined multiple other public servers on ClassiCube including Real's Freebuild Server, a map on which they constructed a headquarters & a shrine to themselves with the help of the user UnixAdmin (who was supposedly not affiliated). The Mr X Cult would usually join servers & spam their name using text blocks most commonly written as "MRX" all over other user's builds. Usually spamming references to their leader Denshi & racial slurs (including the Hard R).
To combat the attack of Mr X on the McGalaxy With Cheese server, the server would come up with the rival to Mr X, known as Mr Y. Mr Y would be portrayed as a Jonestown-like cult leader compared to the grief cult of Mr X. Mr Y would also, as expected, be a furry (specifically a sheep as a reference to Mr X's origins as a farmer).