From Tolkien Gateway

A Tolkienist is someone who studies the work and legendarium of J.R.R. Tolkien.

A Tolkienist can also be described as a hard-core fan of Tolkien's work, one who studies the work with the same amount of interest (or more) that others study non-fictional subjects. Tolkienists can usually be students of the Elvish languages.

There are also other, less widely used terms describing Tolkien fans, such as Tolkienites, Tolkienophiles or Tolkiendili (an Anglo-Quenya compound).

A very early term which was never widely adopted was LotRians. As with the term Ringer, there is no group consensus on this designation. "Ringer" however implies limitation to The Lord of the Rings.