It is with much love and deep sorrow that we mourn the loss of Donald J. Koop of Glenview, IL. Don passed peacefully at home on April 28, 2021 after a long illness and brave battle; he was 73. He was born on May 19, 1947 in Chicago, IL to the late Henry and Valeria, nee Makielski. Don was married for 43 years to his wife and best friend, Terri, nee Bielski, who survives him at home. He is also survived by a daughter, Lin, and her partner, Annie Lane; a sister, Lois (Greg) Repede, a brother, Tom (Karen); and longtime good friend, Terry (Renee) Leight; as well as many cousins, nieces, nephews, and other relatives and friends. Don was an alumnus of Lane Tech H.S., Loyola University and the University of Illinois. Don spent his career in Manufacturing Operations and Human Resources. He found Human Resources more rewarding because he could enhance employee involvement and provide career counseling which gave him great satisfaction. Don had an adventurous personality and enjoyed biking, kayaking, traveling, nature and remodeling projects, but his favorite times were those shared with his wife and daughter, family and good friends. Don's kindness and generosity touched many lives. In keeping true to his wishes, there will be no service and his cremains will be scattered at a later date at the locations he chose. To celebrate Don's life, and his love of biking with family and friends here and in Florida, donations may be made to peopleforbikes.org or to www.stroke.org.