Suggestions by @cw1234

Christina Ricci

as New Villains in Gravity Falls: Dipper and Mabel Return

Kevin Dunn

as Mr Pines in Gravity Falls: Dipper and Mabel Return

Mary Lynn Rajskub

as Mrs Pines in Gravity Falls: Dipper and Mabel Return

John DiMaggio

as Manly Dan in Gravity Falls: Dipper and Mabel Return

James Callis

as Ward in Gravity Falls: Dipper and Mabel Return

Jessica DiCicco

as Tambry in Gravity Falls: Dipper and Mabel Return

Stephen Root

as Bud Gleeful in Gravity Falls: Dipper and Mabel Return

Jennifer Coolidge

as Susan Wentworth in Gravity Falls: Dipper and Mabel Return

Kari Wahlgren

as Priscilla Northwest in Gravity Falls: Dipper and Mabel Return

Nathan Fillion

as Preston Northwest in Gravity Falls: Dipper and Mabel Return

Brad Abrell

as Agent Trigger in Gravity Falls: Dipper and Mabel Return

Nick Offerman

as Agent Powers in Gravity Falls: Dipper and Mabel Return

Austin Butler

as Bill Cipher in Gravity Falls (Live Action Film)

Keith Ferguson

as Deputy Durland in Gravity Falls: Dipper and Mabel Return

Kevin Michael Richardson

as Sheriff Blubs in Gravity Falls: Dipper and Mabel Return

Carl Faruolo

as Grenda Grendinator in Gravity Falls: Dipper and Mabel Return

Niki Yang

as Candy Chiu in Gravity Falls: Dipper and Mabel Return

Thurop Van Orman

as Gideon Gleeful in Gravity Falls: Dipper and Mabel Return

Jackie Buscarino

as Pacifica Northwest in Gravity Falls: Dipper and Mabel Return

T.J. Miller

as Robbie Valentino in Gravity Falls: Dipper and Mabel Return