A Ringer is recent coinage for a fan of The Lord of the Rings — somewhat in the same line as fanboys, fangirls, otaku, and Trekkies, but markedly different. One of the differences is that, whereas also every Star Trek fan is called a Trekker or Trekkie, not all Lord of the Rings fans agree on the designation of the group. Many people who consider themselves fans of Lord of the Rings do not find the posthumously published works of Tolkien like The Silmarillion or The History of Middle-earth to be interesting. Therefore, in some cases Ringer might apply to someone who is a fan of the Lord of the Rings books or movies, but not of Tolkien's extended work. The term 'Ringer' was popularized by TheOneRing.net.
Another popular term is "Tolkienhead."