Illemonati (singular Illemonatus) are Lemon Demon fans.
At its root level, any fan of Lemon Demon technically qualifies as an Illemonatus. However, on the Lemon Demon forum, some unwritten qualifications exist, such as the proper use of English. Those on the forum with poor spelling and grammar are often informally shamed away from the site. This behaviour is likely influenced by the forum’s word filters. Another unspoken qualification is the committing of lemizdat.
Oftentimes Lemon Demon fans without proper English skills, and those that do not commit lemizdat, are not recognized as true Illemonati.