Bonanza fans will of course remember original cast member "Adam Cartwright." Pernell Roberts played the architectural engineer "Cartwright" brother from season 1 until his abrupt exit in season 6. But ...

Pernell Roberts played Adam Cartwright, the eldest and most intellectual of the Cartwright brothers. He left Bonanza after six seasons and later found success starring in the medical drama Trapper ...

Pernell Roberts became famous for playing Adam Cartwright on Bonanza, only to leave the popular Western series well before its final season. /Film. The Real Reason Pernell Roberts Left Bonanza.