J.R.R. Tolkien’s first name was John; his full name was John Ronald Reuel Tolkien.
He was commonly known as Ronald within his family and social circle, while his published name used all three initials. The middle name Reuel came from a family tradition and was also used by Tolkien’s father. The initials became inseparable from his public identity as the author of The Hobbit and The Lord of the Rings.
The form “J.R.R. Tolkien” can make his given names easy to overlook. Ronald was his preferred everyday name from childhood, so biographies and personal accounts often refer to him as Ronald rather than John. His son Christopher also published extensively under the Tolkien name, but the initials J.R.R. specifically identify John Ronald Reuel Tolkien.