​D. Mark McMillan (62), a resident of Wheaton, IL, went to his Lord and Savior Jesus Christ on Wednesday, September 3, 2025, at Northwestern Central DuPage Hospital in Winfield, Illinois, after a four year battle with cancer.  He was born January 30, 1963 in Lincoln, Nebraska to Donald Malcolm & Margaret McMillan.

Mark was raised in California, living in San Diego and Huntington Beach until attending Wheaton College where he graduated in 1985.  In the winter of 1984, Mark met his wife of 40 years, Bethany (Johnston) McMillan while they were students at Wheaton College.  They were married at College Church in Wheaton in November of 1985.  On a whim during his last semester, at Beth's suggestion, Mark took a class in pre-law instead of an elective in photography.  This sparked his interest in the practice of law.  After working as a paralegal and attending law school, Mark began his career with the Chicago law firm Bell, Boyd & Lloyd which he later helped merge with the international law firm K&L Gates.

According to his partners, Mark's journey in law was marked by dedication, excellence, and an unwavering commitment to those he served.  Over his 35 years at his firm, Mark became one of the leading corporate mergers and acquisitions lawyers in the legal industry and was one of the Practice Area Leaders of K&L Gates' global corporate group comprising hundreds of lawyers around the world.  Mark's development and mentoring of numerous lawyers over his career has built a living legacy that will continue for decades.  He is remembered by his colleagues as a paragon of professionalism and a giant in the firm and the legal industry.

In his private life, Mark held a strong faith in Jesus and cared for his family, home, and community.  Mark loved and cherished his wife Beth.  He expressed his faith and served his community at College Church in Wheaton, and later worshiped at Christ Presbyterian Church where he helped the congregation through a building purchase process.

Mark supported Beth in homeschooling their three children and attending various musical and athletic events, and he taught them all to drive stick-shift in his gray-blue Audi TT. Mark enjoyed home-improvement and woodworking projects like helping his children build a multi-storied treehouse, and he kept the house running smoothly in countless ways—his favorite pastime was loading (or reloading) the dishwasher.  He loved all true beauty: harmonious architecture, well-designed spaces and systems, stirring music (classical, classic rock, and bagpipes), Scotland, good food, lavender and rosemary, and reading articles about everything. Ecclesiastes and Job were his favorite books in the Bible.  Justice, wisdom, and loyalty were his nature, and he loved deeply.

He is survived by his wife, Bethany; his children Brendan (Sharon), Matthew (Allison), and Alison; his grandchildren Elise and Amelia; his siblings Scott (Merry) and Kelly (Doug) Schauer.  He was preceded in death by his parents.

A funeral service will be held at Christ Presbyterian Church in Wheaton on Sunday, September 7, at 5:00pm. https://youtube.com/live/MAZv6NTH6u4?feature=share . Memorial gifts, respectfully requested in-lieu of flowers, may be directed to the Christ Presbyterian Building Fund by clicking the "give online" link, then selecting the "Building Fund" in the dropdown menu: Visit the church website at https://www.cpcwheaton.com/giving or click here to donate.