Bill Cipher

Bill Cipher (voiced by Alex Hirsch) is the main antagonist of Gravity Falls. He is a triangular dream demon formerly existent only in the mindscape who wished to gain access to the real world He has been running amok in Gravity Falls, Oregon since being summoned by Stanford Pines over 30 years ago. He is known for his mysterious demeanor and sadistic humor. His plan was to spread was to spread chaos all over the world once he gets to the 3rd Dimension, but in the end he was defeated when the Ford twins switched places making Bill to go into Stan's mind instead of Ford's mind. Once he is in the mind of Stan Pines Mr. Ford uses the memory erasing gun to erase Bill out of existence.

Trivia

 * His design wise looks like the eye of the pyramid on the back of a dollar bill.