Hectorgon is a minor antagonist of the Disney XD series Gravity Falls. He is a demon and an inter-dimensional criminal from an unknown dimension and one of Bill Cipher's friends.
Hectorgon is a red hexagonal demon with arms, big tangerine orange lips, a mustache, a bowler hat with a gold rim (light blue in this picture), and a light blue tie. Hectorgon has a small red aura.
Eons before the events of the series, Hectorgon indulged in criminal activities before being called together by Bill Cipher, along with 8 Ball, Amorphous Shape, Keyhole, Kryptos, Teeth, Paci-Fire, Pyronica, and Xanthar.
In "Weirdmageddon Part 1", during the cold open, Bill introduces Hectorgon with the rest of his demon friends to the residents of Gravity Falls. Afterwards, on Main Street, Hectorgon and the other demons watch Bill turn Ford into a golden statue and taunt Dipper before burning the journals. Later in the episode, Hectorgon is seen playing "Spin the Person" and enjoying the "V.I.P." party Bill is having at the Fearamid, until a calcified statue of Lazy Susan points in the demon's direction and Pyronica happily swallows Hectorgon whole.
In "Weirdmageddon 2: Escape From Reality", Hectorgon and the rest of Bill's minions attempt to leave Gravity Falls and spread their chaos across the world, but are stopped by an invisible barrier, which makes Bill considers getting Ford 'out of retirement'.
In "Weirdmageddon 3: Take Back The Falls", Hectorgon did not participate in the battle against the Shacktron. Following Bill's defeat, he was sucked back to the nightmare realm along with his fellow nightmares.
It's unknown what happened to Hectorgon along with the other Henchmaniacs afterwards.