Fans whose primary or favorite fanac encompasses reading, contributing to and publishing fanzines. Fanzine fan is a retronym, because before the explosion of conventions, nearly all fans were fanzine fans — fanzines were the primary means of communication in fandom until the 1960s.
While many actifen enjoy a full range of fanac, there have always been fans who shun the crowds at cons and clubs and prefer to do their fanac in print. The Hermit of Hagerstown was the most famous example. Fanzine fans tend to be even more introverted and socially awkward than the average fan.
In these days when printed fanzines are few and most fan communication has moved online, many self-identified fanzine fans have not pubbed an ish in years, but the community of former faneds and letterhacks still remains a somewhat cohesive group.