In which TV series is Richie Cunningham a main character?

Who played Fred Sanford in 'Sanford and Son'? Who played Arthur "Fonzie" Fonzarelli in 'Happy Days'? In which TV series is Arthur "Fonzie" Fonzarelli a main character? Who played Richie Cunningham in 'Happy Days'? Who played Charles Ingalls in 'Little House on the Prairie'? In which TV series is Charles Ingalls a main character? Who played Laura Ingalls in 'Little House on the Prairie'? In which TV series is Laura Ingalls a main character?