J.R.R. Tolkien's first name at birth was John.
He was born John Ronald Reuel Tolkien on 3 January 1892 in Bloemfontein, in what was then the Orange Free State. His initials came from his full given names: John, Ronald, and Reuel. He was commonly known as Ronald within his family rather than by his first name.
The name Reuel came from his father, Arthur Reuel Tolkien, and was used as Tolkien's third given name. Tolkien's father died when the boy was young, after which Tolkien and his mother returned to England. His mother, Mabel, played an important role in his early education and interest in languages.
The initials J.R.R. became internationally recognizable through The Hobbit and The Lord of the Rings. Readers sometimes assume the first initial stands for James because of the initials' formal appearance, but Tolkien's birth name was John Ronald Reuel Tolkien.