He is best known for his 14 years as `` Little Joe '' Cartwright in TV 's long-running `` Bonanza , '' and later as Charles Ingalls in nine seasons of `` Little House on the Prairie . '' ` ` ' '' star 's son Mark was found dead in his Hollywood home . Officials found no indication of foul play in year - old 's death . Mark Landon had a few acting credits , playing small roles in three movies .
` ` ' '' star 's son Mark was found dead in his Hollywood home . Officials found no indication of foul play in year - old 's death . Mark Landon had a few acting credits , playing small roles in three movies .