Bill Cipher is the triangular dream demon and main antagonist of Gravity Falls, the Disney animated series that ran from 2012 to 2016 and built a devoted online fandom. His clever, theatrical voice became a favourite for short-form edits after the show ended, as fans clipped his most quotable moments for reaction videos and memes. The character's mix of charm and menace translates easily to new contexts, so a brief Bill Cipher line still signals a smug, knowing twist without needing any explanation of the original scene.