Guest Stars Paget Brewster voices Della Duck Keith Ferguson voices Flintheart Glomgold Josh Brener voices Mark Beaks Keith Ferguson voices Johnny Allison Janney voices Goldie O'Gilt John Gemberling voices Doofus Drake Nicolas Cantu voices B.O.Y.D. Yuri Lowenthal voices Butler Dad Yuri Lowenthal voices Nightmare Beast Eric Bauza voices Beagle Tara Platt voices Doofu's Mom Keith Ferguson voices Percival Noah Baird voices Additional Voices