Henry Winkler Arthur "Fonzie" Fonzarelli Actor Tom Bosley Howard Cunningham Actor Marion Ross Marion Cunningham Actor Anson Williams Warren "Potsie" Weber Actor Cathy Silvers Jenny Piccalo Guest Star Erin Moran Joanie Cunningham Actor Ted McGinley Roger Phillips Guest Star Don Most Ralph Malph Actor Linda Purl Ashley Pfister Guest Star Billy Warlock Leopold 'Flip' Phillips Guest Star Crystal Bernard K.C. Cunningham Guest Star Heather O'Rourke Heather Pfister Guest Star Scott Baio Chachi Arcola Guest Star Pat Morita Matsuo 'Arnold' Takahashi Guest Star Harris Kal Bobby Guest Star Ed Peck Police Officer Kirk Guest Star Kevin Rodney Sullivan Tommy Guest Star Scott Bernstein Melvin Belvin Guest Star Gary Friedkin Clarence Guest Star Ken Lerner Rocco Baruffi Guest Star Jerry Paris Director