The Bill Cipher Wheel (also known as the Zodiac or Cipher Wheel) is a symbol associated with Bill Cipher and the symbols surrounding him. In "Weirdmageddon 3: Take Back The Falls," it is revealed that this wheel is a prophecy used to defeat Bill Cipher.
The wheel is also seen in Journal 2 when Gideon is trying to find out how to summon Bill Cipher. The page in the Journal featuring the wheel looks different than the page featured in the theme song. Some content on the page is the same, and some is different. The page in the journal contains information regarding Bill Cipher, as well as the wheel. The author states that he had been dreaming of Bill and the symbol for weeks, and he questions the significance of the symbol.
As the wheel appears to represent Bill, he seems to have the ability to summon it around him.
In Weirdmageddon 3: Take Back The Falls, Ford reveals that he found these symbols passed down from the natives of Gravity Falls. When each person that correlates with a symbol stands in a drawn version of this wheel and they hold hands, it has enough power to defeat Bill Cipher. Bill Cipher refers to the wheel as "The Zodiac".
The image flashed at the end of the theme song appears to be drawn on a page from one of the journals. The paper has various symbols, writing, and other content written on it including a phrase which can be deciphered with Caesar cipher and reads "STAN IS NOT WHAT HE SEEMS."
When Bill summons the wheel it is a bright, glowing blue. A blue light then flickers around the wheel, briefly highlighting each symbol.
Around the circle are ten small images. These images, their placements, and the people or objects they represent include:
- A pair of glasses: This represents someone who is a scholar, and while Old Man McGucket is the one to stand on the symbol in the finale, it's stated that it has no specific carrier (person). 
- A question mark: Soos Ramirez - Soos' T-shirt
- An open bag of ice: Represents someone who is cool in the face of danger, and Wendy is the one to stand on the symbol in the finale, but it is stated that there is no specific carrier.
- A crescent shaped symbol: Stan Pines - Stan's fez
- A pine tree: Dipper Pines - Dipper's hat
- A crossed, five-pointed star with an eyeball in the center: Gideon Gleeful - the Tent of Telepathy symbol seen on the top of the tent and the back of Gideon's cape
- A hand with six fingers: Ford Pines - the hand on all of the journals
- A llama: There is a llama on one of Mabel's sweaters, which is given to Pacifica Northwest in the finale, who later stands upon the wheel.
- A shooting star: Mabel Pines - one of Mabel's sweaters Also the symbol on Mabel's prison bubble.
- A heart with a stitch in the middle: Robbie Valentino - seen on his sweatshirt.
When seen in "The Stanchurian Candidate," there are several differences in Gideon Gleeful's hand drawn version of the wheel on the wall of his jail cell hidden behind a poster. The arrangement of the symbols used in Gideon's depiction is the same arrangement that Ford uses when drawing the circle in Weirdmageddon 3: Take Back The Falls, but the symbols themselves are drawn as they're seen elsewhere.
- Intro: "Gravity Falls Main Title Theme"
- 119. "Dreamscaperers"
- In Journal 2, on the page with the cipher, the journal has three exclamation points and an arrow pointing to the glasses symbols.
- The crescent symbol representing Stan's hat was originally different but it changed when the symbol on Stan's fez changed in Bottomless Pit. However, the symbol on the wheel as seen in the theme song remains the same.
- Soos', Robbie's, and Dipper's symbols have all been seen elsewhere. As they are all on articles of clothing, there are other articles of clothing with the same symbols on them.
- Several of the symbols on the wheel can be seen on the infinity sided die.
- In the episodes Dreamscaperers, Sock Opera, The Last Mabelcorn, and Weirdmageddon Part 1 Bill calls Dipper, Mabel, Soos, and Ford by their corresponding symbols on the wheel (pine tree, shooting star, question mark, and six-fingers respectively).
- In the apocalypse version of the theme song, the image of Bill is ripped out of the page. This is likely referencing that Bill is now in the real world.
- On the flag to take back Gravity Falls, various symbols from the wheel are there, including the six-fingered hand, the shooting star, the pine tree, and the question mark.
- The order is different in the Cipher Wheel that Gideon drew in The Stanchurian Candidate.
- In this image from The Guide to Mystery, every symbol can be seen. (the stitched heart and llama are hard to see, but they're at the bottom of the page. Only the top half of the heart is visible.)
- Despite some of the symbols being metaphoric (e.g. ice bag and glasses), all of them have been physically seen throughout the series.
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