What was J.R.R. Tolkien’s full first name, including the name represented by the initial R?

J.R.R. Tolkien’s full first name was John Ronald Reuel.

He was born John Ronald Reuel Tolkien on 3 January 1892. The initials J.R.R. therefore represent John, Ronald, and Reuel. “Reuel” was used as a family name and had significance in Tolkien’s family history; Tolkien’s father was Arthur Reuel Tolkien.

The name Ronald was the name by which he was generally known to family and friends in childhood. His surname, Tolkien, came from his paternal family. The author is usually identified publicly by his initials, especially in book titles and reference works, but those initials are not a pseudonym.

The name is sometimes misremembered as John Robert Tolkien because R is commonly used as an abbreviation for Robert in English names. Tolkien’s actual middle names were Ronald and Reuel, making John Ronald Reuel the precise form.