The first name represented by J.R.R. Tolkien’s initials is John.
Tolkien's full name was John Ronald Reuel Tolkien. He was born on 3 January 1892, and “J.R.R.” combines the initials of John, Ronald, and Reuel. The name Ronald was used by family and friends, while the initials became the form most commonly associated with his published work.
The middle name Reuel came from his family naming tradition. Tolkien's father was Arthur Reuel Tolkien, and Reuel was also used in the wider family. The name does not indicate that Tolkien was using a pen name; it was his legal given-name sequence.
Readers sometimes mistake the first initial for James because J.R.R. resembles the initials of other writers, or assume Ronald was his first name because it was commonly used. Bibliographies, birth records, and biographies identify him as John Ronald Reuel Tolkien.