James Mitchell, who for nearly three decades played gruff patriarch Palmer Cortland on the ABC soap opera “All My Children,” has died, his longtime partner said Sunday night. Mitchell died Friday at Cedars-Sinai Medical Center in Los Angeles, partner Albert Wolsky said. Mitchell had suffered from chronic obstructive pulmonary disease for years, complicated by a recent bout of pneumonia. Mitchell appeared in more than 300 episodes of the popular soap from 1979 until a 40th anniversary episode this month. He was a regular on the show until 2008. Born in Sacramento in 1920 and trained as a dancer, Mitchell had leading roles in the Broadway musicals “Brigadoon” and “Paint Your Wagon,” and danced on stage with the American Ballet Theater. His film credits include 1953's “The Band Wagon” with Fred Astaire, 1954's “Deep in My Heart” and 1955's “Oklahoma.”