Suggestions by @cw1234

Sarah Clarke

as New Villains in Gravity Falls: Dipper and Mabel Return

James Sie

as New Villains in Gravity Falls: Dipper and Mabel Return

Kristen Johnston

as New Villains in Gravity Falls: Dipper and Mabel Return

Elizabeth Banks

as New Villains in Gravity Falls: Dipper and Mabel Return

Lena Headey

as New Villains in Gravity Falls: Dipper and Mabel Return

Christopher McCulloch

as New Villains in Gravity Falls: Dipper and Mabel Return

Lance Henriksen

as New Villains in Gravity Falls: Dipper and Mabel Return

James Hong

as New Villains in Gravity Falls: Dipper and Mabel Return

John Noble

as New Villains in Gravity Falls: Dipper and Mabel Return

Jamie Campbell Bower

as New Villains in Gravity Falls: Dipper and Mabel Return

Rami Malek

as New Villains in Gravity Falls: Dipper and Mabel Return

Christoph Waltz

as New Villains in Gravity Falls: Dipper and Mabel Return

Michelle Pfeiffer

as New Villains in Gravity Falls: Dipper and Mabel Return

Miranda Richardson

as New Villains in Gravity Falls: Dipper and Mabel Return

Imelda Staunton

as New Villains in Gravity Falls: Dipper and Mabel Return

Helena Bonham Carter

as New Villains in Gravity Falls: Dipper and Mabel Return

Jason Isaacs

as New Villains in Gravity Falls: Dipper and Mabel Return

Ralph Fiennes

as New Villains in Gravity Falls: Dipper and Mabel Return

Hugo Weaving

as New Villains in Gravity Falls: Dipper and Mabel Return

Mads Mikkelsen

as New Villains in Gravity Falls: Dipper and Mabel Return