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. Eric Bauza voices Beagle Yuri Lowenthal voices Butler Dad Yuri Lowenthal voices Nightmare Beast Keith Ferguson voices Percival Tara Platt voices Doofu's Mom Noah Baird voices Additional Voices