Cast information:
Ron Howard
as Richie Cunningham (1974-1980) --- Ron Howard biography
Henry Winkler
as Arthur "Fonzie" Fonzarelli --- Henry Winkler biography
Tom Bosley
as Howard Cunningham --- Tom Bosley biography
Marion Ross
as Marion Cunningham --- Marion Ross biography
Erin Moran
as Joanie Cunningham --- Erin Moran biography
Anson Williams
as Warren "Potsie" Weber (1974-1983) --- Anson Williams biography
Donny Most
as Ralph Malph (1974-1980) --- Donny Most biography
Pat Morita
as Arnold (Matsuo Takahashi) (1975-1976, 1982-1983)
as Alfred Delvecchio (1976-1982)
as Charles "Chachi" Arcola (1977-1984) --- Scott Baio biography
Lynda Goodfriend
as Lori Beth Allen Cunningham (1977-1982)
as Jenny Piccalo (1980-1983)
as Roger Phillips (1980-1984)
as K.C. Cunningham (1982-1983)
as Ashley Pfister (1982-1983) / Gloria (1974-1975)
as Heather Pfister (1982-1983)
as Chuck Cunningham (1974)
as Chuck Cunningham (1974-1975)
as Bag (1974-1975)
as Marsha (1974-1976)
as Wendy (1974-1975)
as Trudy (1974-1975)
as Flip Phillips (1982-1983)
as Officer Kirk (occasional)
as Eugene Melvin (1980-1982)
as Bobby (1980-1984)
as Tommy (1980-1984
as Mickey Malph (occasional)
as Pinky Tuscadero (1976/3 episodes)
as Leather Tuscadero (several appearances)
as Melvin Belvin (1981-1983) --- Scott Bernstein biography
Danny Butch
as Spike Fonzarelli (several episodes)
You can go to the direct link
to the Internet Movie Database's entry for Happy Days at: http://us.imdb.com/Details?0070992