William H. "Mike" McMillen, age 75 of Glen Mills, PA passed away on April 7, 2021 at his home surrounded by his loved ones. Born to Adrian F. and Eleanor Wilson McMillen in Spartanburg, SC, he was raised in Blossburg, PA, and resided locally in Upper Providence and Glen Mills, PA. William was a math teacher at Haverford High School from 1968 to1999. He also coached both boys' and girls' track and cross country teams for 37 years, 27 years at Haverford High School and 10 more years at other local and private high schools. Track brought Mike much happiness in his life and he proudly ended his career with an overall record of 577 wins-124 losses (and 29 central league championship teams). William liked playing bridge with his friends but most of all, his greatest joy was watching his son and grandsons play sports. In addition to his parents, William is preceded in death by his brother, John (Lella) McMillen, he is survived by his loving wife, Ruth E. Henger McMillen of 51 years, his son Matt (Michelle) McMillen, sister Peggy (Ron) Allen, his 3 grandchildren; Cameron, Hudson, and Everly, nephews, David Allen and Michael McMillen, and nieces, Margot McMillen and Barbara Allen. Funeral services will remain private at this time. Donations in his memory may be made to Shriners Hospital for Children (https://www.shrinershospitalsforchildren.org/shc) or Tunnel to Towers foundation (https://tunnel2towers.org/). Online condolences may be made by visiting www.paganofuneralhome.com.