Exopedianism is the philosophy of focusing on the encyclopedic side of Wikipedia (articles and related content) rather than the social and institutional side of the project. Users who practice the philosophy are called exopedians and fall on the opposite end of the spectrum from metapedians. Mesopedians lie somewhere between the two.
Exopedians may seem cold and aloof to some other users, due in part to a personal focus on contributing and editing content on Wikipedia rather than interacting with users. They may not even bother having a Wikipedia account, instead making all their edits anonymously. However, they may interact on certain internally related areas of Wikipedia when articles they are focused on are altered in some fundamental ways: merging, deletion, becoming a Featured Article, etc.
There is currently no organized group for exopedians (as there is for metapedians), and it is unlikely that there will ever be one since an organized group would be contrary to exopedianism itself.
There is, however, a category and a userbox -- Wikipedia:Category:Exopedianist Wikipedians -- for users who identify as Exopedianist.