Stan's six-fingered long-lost identical twin brother and the mysterious person who wrote all three of the journals. He returns from an alternate dimension through a portal underneath the Mystery Shack in "Not What He Seems" after being absent since 1982. In "The Last Mabelcorn", he recounts his friendship with Bill Cipher and how he attempted to create a teleporter to enter his realm. In the present, when he learns of Bill's plan to invade the mainstream dimension, he destroys the teleporter, but at the cost of a dimensional rift leaking out of it, which he contains. In "Dipper and Mabel vs. the Future", Bill tricks Mabel into releasing the rift, causing Weirdmageddon. In "Weirdmageddon Part 1" he attempts to defeat Bill, but is captured, petrified and his journals are destroyed. He is later freed and restored of his humanity. After Weirdmageddon, he tells Stan that he found some remaining anomalies and offers him to go sailing around the world to find them, which Stan accepts.