Dennis P. O'Brien, 88, passed away peacefully Oct. 16, 2021, after a two-year battle with ALS, Lou Gehrig's disease.
Dennis, or Big D, was born in 1933 in the Bronx, New York, the third child of William O'Brien and Nellie (Sugrue) O'Brien.
Dennis attended St. Angela Merici Elementary School and Cardinal Hayes High School. During the Korean War, he enlisted in the U.S. Navy on St. Patrick's Day in 1952 and served four years as a U.S. Navy Hospital Corpsman assigned to the U.S. Marines.
Upon returning from service, he earned his bachelor's in finance and economics from Iona College. During this time, he also met his ever love, Suzanne Devlin. Dennis and Sue were married on Feb. 4, 1961, and raised five children. They lived in Hinsdale and Burr Ridge for 35 years.
Dennis spent the majority of his professional life in sales and owning and operating his own outdoor advertising business. When he sold his company to a major outdoor advertising entity, he became a partner helping to take the company public. He spent the next 15 years advising outdoor companies to expand internationally into China, while developing the country's airport and highway advertising business.
Never willing to retire, he stayed active until COVID arrived and his diagnosis of ALS was made by Mayo Clinic. He was known as an intense and passionate negotiator, competitor and dealmaker.
Dennis played basketball in the service for the elite Marine basketball team, and never stopped playing competitively. He retired from basketball at 85, the same year his team won the "Gold" in the National Senior Games. He was awarded the MVP of the games and inducted into their Basketball Hall of Fame.
Dennis' children were always uppermost in his mind and his pride and love for them was ever present. His calls for a breakfast date with each are legendary. Attending his kids' and grandchildren's sporting events were premier occasions for him, and the loudest voice from the stands was always his. If he missed a game, the call came that they needed "The Voice" back cheering them on.
Faith, family, and country governed his life. His strength, kindness, courage and sense of humor remained to the end, along with his unwavering belief in the dear Lord. He was inspirational to those who knew him and deeply loved in return. Dennis is survived by his wife of 60 years, Sue; his five children, Dennis (Laura), Kathryn (Bryan) Kumler, Erin (Richard) Pietranek, Ellen (Jim) Paul and Peter (Natalie) O'Brien; and his nine grandchildren, Shawn O'Brien, Reiley and Grady Kumler, Sophie, Maddie and Danny Pietranek, Jack and Sarah Paul, and Leela O'Brien.
He was preceded in death by his brothers, Bill and John; and his sister, Joan (Vogt).
Visitation is from 4 to 8 p.m. Friday Oct. 22, in Leppert Mortuary, Nora Chapel, 740 E. 86th St., Indianapolis.
A Mass will be celebrated at 10:30 a.m. Saturday, Oct. 23, at St. Luke's Catholic Church, 7575 Holiday Drive E., Indianapolis.
Interment will be private.
