The final volume of J.R.R. Tolkien’s The Lord of the Rings was published in 1955.
The Return of the King, the third volume, appeared on 20 October 1955. The first volume, The Fellowship of the Ring, had appeared in 1954, followed by The Two Towers in the same year. Publication was delayed by Tolkien's revisions, production issues, and the difficulty of preparing such a large work.
Although the work is commonly called a trilogy, Tolkien conceived it as a single long story divided into six internal books, with appendices. The three-volume format was partly a publishing decision, influenced by paper shortages and the practical cost of producing a large novel in postwar Britain.
The 1955 date refers to the original publication of the final volume, not to the later popular editions or the film trilogy. The Return of the King concludes the main narrative with the defeat of Sauron and the restoration of order in Middle-earth.