PAT STEPHEN DRENNAN, age 89, died January 20, 2011 at Silverado Senior Living in Irving, Texas from a stroke. Born October 30, 1921 in Lone Willow, Johnson County, Texas to John Stephens Drennan and Louna Jane Smith, he was raised on farms in Johnson and Floyd Counties in Texas. Pat graduated from the University of Texas at Austin in 1945 as a chemist. He had a long career in the petroleum, nuclear and space industry as an engineer and manager receiving a number of patent awards for refinery processes. Retired since 1975, Pat enjoyed hobbies of photography and genealogy. Preceded in death by his parents and two wives, Orpha LaVerne Hale and Barbara Hewitt; and his brother, James Harris Drennan, he is survived by two sons, Stephen Austin Drennan and wife Kay Drennan, Clarence Alan Drennan and wife Eileen Drennan, both of the Dallas area; grandchildren, Ronald, Shelly, Jeffery, Katherine and David; numerous great grandchildren; his sister, Dorothy Jean Moser of Cleburne, Texas; sister-in-law, Evelyn Angeline Drennan of Arlington, Texas; and numerous nieces and nephews. In lieu of floral arrangements, please consider a donation to the Alzheimers Association.