Tolkien fandom is an international, informal community of fans of the works of J. R. R. Tolkien, especially of the Middle-earth legendarium which includes The Hobbit, The Lord of the Rings, and The Silmarillion. The concept of Tolkien fandom as a specific type of fan subculture sprang up in the United States in the 1960s, in the context of the hippie movement, to the dismay of the author (Tolkien died in 1973), who talked of "my deplorable cultus".

A Tolkienist is someone who studies the work of J. R. R. Tolkien: this usually involves the study of the Elvish languages and "Tolkienology". A Ringer is a fan of The Lord of the Rings in general, and of Peter Jackson's live-action film trilogy in particular. Other terms for Tolkien fans include Tolkienite or Tolkiendil.

Many fans share their Tolkien fan fiction with other fans. Tolkien societies support fans in many countries around the world.

Tolkien's The Hobbit, a children's book, was first published in 1937, and it proved popular. But The Lord of the Rings, first published in three volumes in 1954 and 1955, gave rise to fandom as a cultural phenomenon from the 1960s onwards.

Tolkien fandom began within science fiction fandom soon after The Fellowship of the Ring was published in 1954. Tolkien was discussed in science fiction fanzines and amateur press association magazines ("apazines"), both as single essays like "No Monroe In Lothlorien!" in Eric Bentcliffe's Triode, and in extended threads of comment such as by Robert Lichtman in his Psi Phi. Tolkien-inspired costumes were worn at Worldcons from 1958. An organized Tolkien fandom organization called "The Fellowship of the Ring" came together in Pittcon, the 18th World Science Fiction Convention in Pittsburgh on 4 September 1960.

England's first Tolkien fanzine was Nazgul's Bane, produced by Cheslin. Many fanzines had little Tolkien content but Tolkien-inspired names such as Ancalagon, Glamdring, Lefnui, Mathom, Perian, Ringwraith, Shadowfax, and so on. Others had more meaningful Tolkien content. Ed Meskys' apazine Niekas turned into a full-fledged fanzine during this era. Pete Mansfield's Sword & Sorcery fanzine, Eldritch Dream Quest, included many Tolkien items.

Foster attributes the surge of Tolkien fandom in the United States of the mid-1960s to a combination of the hippie subculture and anti-war movement pursuing "mellow freedom like that of the Shire" and "America's cultural Anglophilia" of the time, fuelled by a bootleg paperback version of The Lord of the Rings published by Ace Books followed up by an authorised edition by Ballantine Books. The "hippie" following latched onto the book, giving its own spin to the work's interpretation, such as the Dark Lord Sauron representing the United States military draft during the Vietnam War, to the chagrin of the author who talked of a "deplorable cultus" and stated that "Many young Americans are involved in the stories in a way that I'm not" but who nevertheless admitted that "... even the nose of a very modest idol [...] cannot remain entirely untickled by the sweet smell of incense!" Fan attention became so intense that Tolkien had to take his phone number out of the public directory.

The embracing of the work by American 1960s counter-culture made it an easy target for mockery, as in Harvard Lampoon's parody Bored of the Rings, where Tom Bombadil becomes "Tim Benzedrine", and Bilbo Baggins becomes "Dildo Bugger". The Lord of the Rings acquired immense popularity in the emerging hacker culture from the mid-1960s, and the technological subcultures of scientists, engineers, and computer programmers. It figured as one of the major inspirations of the nascent video game industry and the evolution of fantasy role-playing games.