Pernell Elvin Roberts, Jr. (May 18, 1928 – January 24, 2010) was an American stage, movie and television actor as well as singer. In addition to guest starring in over 60 television series, he was widely known for his roles as Ben Cartwright's eldest son, Adam Cartwright, on the western series Bonanza, a role he played from 1959 to 1965 — and as chief surgeon Dr. John McIntyre, the title character on Trapper John, M.D. (1979–1986).