In Song of Susannah, Roland and Eddie encounter the real-life author Stephen King during their interdimensional travels.
Using a magical doorway, the pair arrive in Maine in 1977, where they discover that Stephen King exists as a person in the story’s world. King is writing—or has begun writing—the events surrounding Roland’s quest, creating a metafictional link between the fictional Dark Tower saga and its real-world author.
The meeting is deliberately unsettling: Roland and Eddie realize that the man who appears to have created their world may instead be recording events transmitted to him by forces connected to the Tower, the Beams, and ka. Roland tries to persuade King to continue writing, because the ka-tet comes to believe that their quest depends on the story being completed.
A common mix-up is the book’s title: it is officially Song of Susannah, singular, and it is the sixth main novel in The Dark Tower series. King also appears more extensively in the seventh book, The Dark Tower, but Roland and Eddie first meet him in Song of Susannah.