Bill Cipher

Bill Cipher is a two-dimensional interdimensional demon, formerly existent only in the Mindscape before succeeding in gaining access to the real world. He had been running amok in Gravity Falls, Oregon since being summoned by Ford Pines over thirty years ago. Known for his mysterious demeanor and sadistic humor, Bill is the main antagonist of the overall series.

Bill is a cunning, blasphemous, eccentric, sadistic, psychopathic and physically irreverent being who finds most things amusing, particularly if they cause distress or harm to others. He is outrageous and outlandish, as well as a quick talker and thinker. Though he may come across as simply annoying, he shouldn't be underestimated; for when he is angered, he is a force to be reckoned with as he will unleash his near-omnipotent powers on those unfortunate enough to make him angry. When accused of being insane, Bill proudly agrees with the statement. He is also shown to be somewhat obnoxious, as seen when he makes his presence known to Dipper when the latter is trying to figure out a password within a limited amount of time. occasionally, his voice tumbles to a lower pitch (usually when emphasizing a statement).

As a demonic dealmaker, Bill is also shown to be a highly manipulative, very charismatic and charming conman being able to easily trick Ford Pines into believing that he was just a humble muse who simply wished to help benefit the human world by providing him with forbidden knowledge when in reality he was only ever using the researcher for his own purposes with Ford noting that the only person who could've possibly seen the ruse for what it was, was his brother Stan Pines, who was himself an expert conman.

Bill is not one who believes in rules. Instead, he follows his own selfish philosophy which means doing whatever he wants without care for the consequences. He thinks of laws and physics as senseless and displays an irresistible urge to break those rules down by causing absolute chaos however he can. The lives he ruins hold no merit to him and he finds amusement in tormenting and turning people's worlds upside-down. He also sees reality as "an illusion" and values its destruction.

When possessing Dipper's body, Bill is shown to be rather masochistic, hurting himself in various ways for the thrill of it, exclaiming that "pain is hilarious." He seems to have little knowledge about the human body, specifically its physical limits. This comes back at him when he fights Mabel over Journal 3, as he eventually falls down, exhausted.

As shown in "Weirdmageddon Part 1," he also reacts sadistically whenever a would-be subject oversteps their boundaries, such as when he shuffles "the function of every hole in Preston Northwest's face", and in "Weirdmageddon 3: Take Back The Falls" when he decides to kill one of the Pines twins "just for the heck of it."