Ferb – Levi Miller
The quiet Abbott to Phineas’ loud Costello, Ferb is a less showy part on paper. Yet his unflappability is an essential part of the show’s DNA. In the film version, Levi Miller would be the perfect anchor. We’ve seen him project comfort and calm in works like A Wrinkle In Time. Dye his hair green, turn his native Australian accent British, you’ve got yourself a Ferb.