Pete Davidson Marmaduke (voice) J.K. Simmons Zeus (voice) David Koechner Phil Winslow (voice) Mary Hart EntertainMutt Tonight Host (voice) Julie Nathanson Dottie Winslow (voice) Terri Douglas Billy Winslow (voice) Erin Fitzgerald Barbara Winslow (voice) Stephen Stanton King Tut (voice) Brian Hull Guy Hilton (voice) Sumalee Montano Amy (voice) Andrew Morgado Henri / Phillipe (voice) Chris Hackney Announcer (voice)