Duncan Munroe O'Brien, 83, of Denver, died Thursday, January 20th. Born in Albany, N.Y. on August 16, 1927, he was the son of the late John Larkin O'Brien and the late Isabel Munroe O'Brien. He lived in Denver for nearly 60 years. Mr. O'Brien was a 1945 graduate of Milton Academy and a 1950 graduate of Yale University. He served in the U.S. Marine Corps Reserves from 1945-1946. For a brief period after graduation, he worked in the Bank Examinations Department of the Federal Reserve Bank of NY before relocating to Colorado to pursue his passion for skiing and the West. He worked as a roughneck and as a landman in the oil & gas business before founding his business, Neoga Oil Company, Inc., which was named after a yacht he loved. He remained active in the oil & gas business all of his life. He was a member of The Denver Country Club and The Denver Athletic Club and a former member of The University Club and The Yale Club of New York City. He loved being with family and friends, swimming in the ocean, playing golf and bridge, and sharing stories and jokes. He is survived by his special friend and companion Joyce Glober Herbert; his former wife and the mother of his children, Edna Lee O'Brien of Westport, CT; four sons, Duncan Munroe O'Brien, Jr. of Westport, CT, Douglas Drake O'Brien of Highlands Ranch, CO, Stewart Larkin O'Brien of Los Alamos, NM, and Malcolm Edward O'Brien of Lakewood, CO; three daughters-in law, Jennifer, Jodi, and Melissa; a sister, Patricia O'Brien Parsons of Burlington, VT; a sister-in-law Anne Buffinton O'Brien of Tiverton, RI; nine grandchildren, Elizabeth Crary, Duncan Munroe III, Katherine Anne, Caroline Lee, Margaret Louise, John Larkin, Chelsea Lynnae, Lauren and Ethan; and five nieces and nephews. His brother, John Larkin O'Brien, Jr., preceded him in death. In lieu of flowers, the family requests that memorial contributions be made to Mimi's Building Blocks (c/o Save the Children, 54 Wilton Road, Westport, CT 06880) to support the education of children in Ethiopia, an organization founded by a lifelong friend, Mimi O'Hagan. A memorial service celebrating his life will be held on Friday, January 28, 2011, at 11:00 am at Christ Episcopal Church, 2950 S. University Blvd. Burial will be private. Horan & McConaty, 1091 S. Colorado Blvd., Denver, is in charge of arrangements.