In which TV series is Charles Ingalls a main character?

In which TV series is Arthur "Fonzie" Fonzarelli a main character? Who played Richie Cunningham in 'Happy Days'? In which TV series is Richie Cunningham a main character? Who played Charles Ingalls in 'Little House on the Prairie'? Who played Laura Ingalls in 'Little House on the Prairie'? In which TV series is Laura Ingalls a main character? Who played George Jefferson in 'The Jeffersons'? Who played Vinnie Barbarino in 'Welcome Back, Kotter'?