Bill Cipher is the main antagonist in Gravity Falls. He is a powerful dream demon that can be released into a person's mind. Bill is a one-eyed, yellow, triangular pyramid with a top hat and a bow tie. He is a powerful being in the form of "The Eye of Providence" (therefore showing his connection with Freemasonry). He tends to have a sense of humor, however he loses his temper quite easily and has great powers.
- Bill Cipher was voiced by Alex Hirsch, who also voiced Stanley Pines, Soos and Old Man McGucket.