What was the name of J.R.R. Tolkien’s first published book?

J.R.R. Tolkien’s first published book was The Hobbit, released in 1937.

The full title is The Hobbit, or There and Back Again. It follows Bilbo Baggins, who leaves the Shire with Thorin Oakenshield and a company of dwarves to reclaim treasure from the dragon Smaug. The book began as a children’s fantasy but attracted readers of many ages.

The Hobbit introduced characters, places, and ideas that Tolkien later connected to the larger mythology of Middle-earth. Its success encouraged Tolkien’s publisher to request a sequel, leading eventually to The Lord of the Rings.

The Silmarillion was published after Tolkien’s death, in 1977, through Christopher Tolkien’s editorial work. Leaf by Niggle is a shorter story, and The Lord of the Rings came later. Thus the answer concerns Tolkien’s first published book-length work, not his earliest poem, essay, or scholarly publication.