Jeff Mackay lived large. A technology evangelist, skilled woodworker, and design enthusiast, he embraced change and challenge with open arms. Always ready with a joke and friendly to a fault, he loved welcoming people into his home and his heart. Jeff lived on his own terms straight to the end — on June 4, 2026, he passed unexpectedly while traveling between a family visit and a Pokémon Go event.

Jeffrey Charles Mackay was born on August 27, 1963, in Waukesha, Wisconsin, to William Frederick Mackay and Avon Jean Mackay (LaRue). He enjoyed a rambunctious childhood as the fifth of seven kids, including an infamous summer that racked up 11 ER visits to Waukesha Memorial. After graduating from Waukesha North in 1981, college plans proved financially out of reach. Jeff joined the Air Force — a decision influenced, at least in part, by the superior cocktail selection at the recruiting station. He was stationed in Arizona and then South Korea, where he excelled in administration before being identified for computer science training that would go on to define his career. He also spent time volunteering at a local orphanage, perhaps feeling the pull of the big family he'd left behind. It was in Korea where he met and married his first wife, Mi Suk Nam, and where his first child, Linda Marie, was born in 1985. The family then moved to Alabama, where his son Daniel Patrick was born in 1986.

After leaving the Air Force, Jeff and his family settled in Lilburn, Georgia, where he continued to develop his software skills and published a book on C++ programming. In 1995, he moved with his family to Illinois to work with Andersen Consulting on the foundations of object-oriented programming. He went on to found two software start-ups while Linda and Dan attended middle and high school in Lake Zurich. In 1998, while traveling for work in Missouri, he met his future wife, Megan Fedders. They married in 1999 and relocated from Illinois to Wisconsin in 2002, where Jeff joined his brother Tim Mackay as a software architect at GE Healthcare. In 2006, Jeff and Megan welcomed Alexander (Zeke) Mackay to the family, and Jeff happily climbed back onto the parenting carousel for a second stint.

In 2007, Megan and Jeff took the plunge on a lot in Hartland, and Jeff oversaw the building of their dream home — complete with a large workshop for his woodworking. With space for kids, in-laws, and friends, the two built a warm and tight-knit circle through Four Winds, Swallow School, and BSA Troop 47. Linda and Dan both settled in Atlanta and married Georgians, but made frequent trips to Wisconsin for cold weather, cheese curds, and dad jokes. Jeff was blessed with two grandsons, Ezra (2021) and Elias (2025). His youngest, Zeke, graduated from Arrowhead High School in 2024 and is currently a junior at UW–Madison.

In 2025, Jeff retired from GE Healthcare and poured himself into what he loved most: helping family members and connecting with fellow Pokémon Go enthusiasts across the country. He continued to thrive on time with his children, grandchildren, friends, and neighbors, and remained devoted to Megan, his wife of 27 years. Jeff will be acutely missed by all who knew him. He is preceded in death by his parents and his brother Chris Mackay. He is survived by his wife Megan Fedders, siblings Jeanne (Bill) Prue, Kerry (Terry) Mackay, Kathy (Bill) Rankin, Tim (Kate) Mackay, and Steve (Toni) Mackay, and children Linda (Marc) Ross, Dan (Hillary) Mackay and Zeke Mackay. He will also be missed numerous neices and nephews, in-laws, friends, neighbors and by the whoodles, Ziggy and Lola.

A memorial service for Jeff will be held at Lake Country Unitarian Universalist Church (W299 N5595 Grace Dr, Hartland, WI 53029) on June 27th at 1:00pm. We'll have a visiting hour from 12:00-1:00 and informal story sharing will immediately follow the service at 2:00.