Bill Cipher

Bill Cipher is a dream demon that can enter a person's subconscious. He can be summoned using an incantation found on his page in Journal 2 under certain conditions: "Triangulum, entangulum. Veneforis dominus ventium. Veneforis venetisarium!", which, translated from its original Latin, approximates to: "Triangle, I invoke you. I come to the defensive barrier of the mind. I will see the barrier destroyed."

History
At some point before the events of the series, the author of "1," "2" and "3" came across him, recording his powers and appearance in the books.

Bill and the symbol he's based on, the Eye of Providence, appear frequently in Gravity Falls. He was the unseen creator of the cryptograms in the online game Rumble's Revenge. His name and existence is deduced by taking all the capital letters in the cryptograms from Rumble's Revenge, to form the message: "MY NAME IS BILL."

A picture of Bill is shown briefly at the end of the opening theme. A similar picture is seen in the entry about him in book 2. Encircling him are various symbols that link to various characters in the show. Most notably, when he appears physically for the first time, he refers to Dipper, Mabel, and Soos, as "Pine Tree, Shooting Star, and Question Mark" respectively. The entry also makes special note of the glasses symbol, the author of the book seemingly having been alarmed by this. Underneath "Name: ???" is the text: "This odd, triangular being has appeared in my dreams every night for weeks."

His full name appears in his entry in book 3. Behind his name is a message encrypted with a symbol substitution cipher; when decoded it reads: "Liar Monster. Snappy Dresser." There are various notes scattered about the page, such as "Is he watching me?" and "Bill has proven himself to be one of the friendliest and most trustworthy individuals that I've ever encountered in my life. What a guy! I honestly can't trust him more. Not evil in any way, Bill is a true gentleman." However, the latter note is crossed out and below another note reading "Can't Be Trusted!" can be found written in red ink. On the next page, a diagram of a human head and various aspects of its mind is shown, its top being opened up for a drawing of Bill to enter it. In the lower right corner of the page "DO NOT SUMMON AT ALL COSTS!" is written in large, red letters. The rest of the page is spattered with a dark red substance...

"Dreamscaperers" is the first time Bill is directly addressed and introduced in the series. Gideon Gleeful, in an attempt to take over the Mystery Shack once again, summons him. Gideon tells him to steal Stan's safe combination directly from his head, so that Gideon can steal the Shack's deed. Bill agrees once he knows it's Stan, but in return Gideon would have to help him in his own plans, which are not revealed to the viewer. Gideon agrees immediately and the two shake on it. Unbeknownst to Gideon, Mabel and Soos witnessed the deal in the forest, and get Dipper's help to follow him into Stan's mind.

Once inside Stan's head, Bill confronts the trio, and brags that he knows what they're all thinking. To prove his statement, he summons Xyler and Craz from Mabel's imagination. He tricks Mabel and Soos into looking for the memory of Stan's safe combination first, knowing they'd lead him straight to it. At some point Soos is separated from everyone else, and Bill takes his place. Once they find the correct memory he takes it and nearly escapes with it. But while he reads the combination out loud to Gideon (to whom he was connected), Mabel shoots the memory door into another memory of the bottomless pit with a nyarf dart. Gideon breaks off their deal, to Bill's fury. Bill turns his anger toward Mabel and Soos by bringing their nightmares to life and killing Xyler and Craz.

Dipper returns in a timely manner and tells Mabel and Soos that while they are in Stan's mindscape they can do whatever they want. They battle Bill and he is nearly defeated. And just as though it seems he will be forced out of Stan's head, he puts a stop to everything instead. Impressed, he decides to let them go, and after warning them of a mysterious darkness that will change everything they care about, he tells them that he'll be watching them. He leaves in a wheel almost identical to the one that appears in his entry in book 2.

Bill reappears again in "Sock Opera" for the first time in season 2, when Dipper is trying to figure out the password for the laptop from "Into the Bunker". He offers the laptop's password in return for a favor he wants, but Dipper refuses the offer. Later, at the moment the laptop is on countdown for complete data erase after too many failed password entries, he appears again and Dipper accepts the deal of trading a puppet to obtain the password. Bill takes over Dipper's body as his "puppet" and destroys the laptop. He then follows Mabel to her puppet show in pursuit of Dipper's journal that is being used as a prop in the show. After Mabel has been informed of Dipper's body having been stolen by him, he finds her with the journal as she is retrieving it for Dipper. He almost swindles her out of it but ends up in a fight with her. He ends up losing because Mabel uses Dipper's physical weakness and exhaustion to her advantage. As he collapses, he is thrust out of Dipper's body.

Bill possesses the Dipper puppet afterward and says that he will return. However, Mabel lights the pyrotechnics, which destroy the puppets.

Personality
Bill is an insane and physically irreverent demon who finds most things amusing (although no one is really sure why). He's outrageous and outlandish, as well as a quick talker and thinker. Though he may come across as simply annoying, he's not to be taken lightly; when angered, he's a force to be reckoned with.

Appearance
Bill is a yellow, triangular creature that bears a strong resemblance to an Egyptian Pyramid and the Eye of Providence. He has a single large eye rimmed with four short black lashes on its top and bottom. He moves around mostly by floating about, and rarely actually stands on his own two feet. He has thin, black limbs, wears a small, black bow tie, and has a tall, thin, black top hat that floats just above his head. His arms do not seem to be in any fixed position, and can be moved along his perimeter without any difficulty. He has also been seen carrying a small, black cane which turned yellow in Season 2. When he gets mad, he turns red and his eye glows light red.

Summoning ritual
To summon Bill Cipher, you'll need a picture of your victim. Cross out the eyes and put 8 candles around it in a circle. Say the following spell: "Triangulum, entangulum. Veneforis dominus ventium. Veneforis venetisarium!" Your eyes will glow blue. You'll say "backwards message" backwards 5 times. A triangle appears. One eye opens and it turns into Bill's normal appearance. However, it is shown that Bill has the ability to temporarily pull other beings into his plane of existence, if he so pleases, as seen in Sock Opera.

Preventing Bill's chaos
In order to prevent Bill's chaos inside someone's mind, one must light nine candles and place their hand on the victim's forehead. Say the following incantation: ''Fidentus omnium. Magister mentium. Magnesium ad hominem.Magnum opus. Habeas corpus. Inceptus Nolanus overratus. Magister mentium. Magister mentium. Magister mentium.'' If spoken the reciter of the incantation's eyes will turn blue and will be brought to the victim's mind on how they picture, where they have to find a way to stop Bill themselves.

Abilities
Bill's abilities are focused around the mind and mental manipulation. He's described as a "dream demon" and displays some of the characteristics of a demon including creating contracts with his summoner. When he is summoned, he appears to put everyone and anyone observing into a trance-like dream. The effect is that the world seems to turn colorless, and he can effect the surrounding environment however he likes, as demonstrated by pulling out and returning a deer's teeth. The people observing are unaware they've fallen asleep until Bill leaves and then they realize their eyes have been closed during his whole meeting.

Bill can enter people's minds through their dreams. Once inside a mind he can manipulate anything, including his shape and form and changing the landscape. He can communicate with his summoner like a video call, using his body as a window. In fact he can use his whole body as projector and display images. His body also seems to lead to a pocket space and runs in a slightly different time. (e.g., Mabel jumps into Bill's body and several seconds pass before she reappears, none the wiser.)

Once inside of a mind he can also easily pluck information from any others who are also inside and bring those ideas and images to life. The conjured images seem to take a life of their own such as the case with Xyler and Craz.

Bill is also at least close to omniscient. He knows "lots of things," including the truth of many well known conspiracies as well as future events, such as the destruction of Gideon-bot and that Gideon Gleeful would go to prison.

Bill also has the ability to remove people's souls from their bodies, and take possession of the body afterwards. The person who is removed from their body is stuck in a ghost like form in the dream scape, unable to affect the rest of the world, unless they find a vessel. This vessel doesn't have to be a living thing, as Dipper, who was a victim of this, used Mabel's sock puppets to warn her.

Cameos
The following are sightings of Bill and the Eye of Providence outside his physical appearance

Quotes
"Deer teeth. For you, kid!"

- Bill Cipher

"It's funny how dumb you are!"

- Bill Cipher

"Remember, reality is an illusion, the universe is a hologram, buy gold, bye!"

- Bill Cipher

"A darkness approaches. A day will come in the future where everything you care about will change... Until then I'll be watching you! I'll be watching you..."

- Bill Cipher

"Look kid, you've been getting way too close to figuring out some major answers. I've got big plans comin' and I don't need you gettin' in my way. Destroying that laptop was a cinch. Now I just need to destroy your journal."

- Explaining the reason why Bill destroyed Dipper's laptop

Trivia

 * He is based on the Eye of Providence, which is most commonly seen on the back of the American dollar bill.
 * His name is a combination of Bill, possibly referring to eye of providence, which appears on dollar bills and cipher, which is the algorithm for encryption or decryption.
 * His name may also be an allusion to the Beale Ciphers, a set of three ciphertexts, one of which allegedly states the location of a buried treasure of gold, silver and jewels estimated to be worth over USD $63 million as of September 2011.
 * On the page about Bill in book 2, the -$12 bill says "Semper vigilantem", which in Latin means "always watching".
 * Bill has been shown to ignite a blue flame in his hand in order to seal a deal with one of his clients. This has been shown in both Dreamscaperers and Sock Opera
 * Both journals 2 and 3 contain sections on Bill, but whereas journal 2 contains instructions on how to summon Bill, journal 3 contains instructions on how to stop Bill if he is summoned.
 * Additionally, Journal 2 states that his name is not known, while Journal 3 gives the name Bill Cipher.
 * In the game Rumble's Revenge, one of the translated cryptograms says "i will be returning to gravity falls ……….," foreshadowing his appearance in "Dreamscaperers."
 * When Bill Cipher states that "Reality is an illusion, the universe is a hologram," he is referencing both Einstein and The Matrix.
 * In "Dreamscaperers," Gideon summons Bill with an incantation or spell of some sort. In reverse, Gideon is simply saying "backwards message" repeatedly.
 * In Sock Opera, when possessing Dipper, he states "It's been so long since I've inhabited a body!" suggesting he's either had a body before, or has taken another's body before.
 * David Lynch of Twin Peaks fame was originally offered to voice Bill, but when he declined the offer, Alex Hirsch just did a "bad impression of him".
 * He likes silly straws simply because they are "silly", as well as pulling teeth out of a deer's mouth, making time stop forever, and transforming into what people fear most.

Bill Cifra Билл Шифр