Jeff Derr, 37

Jeffery “Jeff” Derr, 37, passed away unexpectedly on June 25, 2026, in Sidney, Montana, from a heart attack caused by a congenital heart defect. His passing came just days before his planned wedding at Makoshika State Park.

Jeff lived with intention, joy, and authenticity. Born with a heart condition that made every year a gift, he embraced life fully and on his own terms. He was known for his protective nature, quick wit, creativity, and steady kindness. Friends and family remember him as hardworking, thoughtful, and always ready to bring laughter into any moment through his playful spirit.

Jeff was proud of his work as an apprentice electrician with Prairie Electric and was working toward becoming a journeyman. Those closest to him admired his determination and the way he pursued his goals with conviction.

At home, Jeff and his wife, Stephanie Hartless, built a life around simple joys, shared projects, and time spent with friends and family. They enjoyed tending their garden, taking day trips, exploring back roads with their dogs, Jellybean and Daisy, and dreaming up new projects for their home.

Family was at the center of Jeff’s life. He was the beloved younger brother of several devoted sisters and shared deep bonds with cousins who felt more like siblings. He was a devoted uncle who delighted in his nieces and nephews and proudly embraced the nickname “Uncle Cousin Jeff.” Whether through family karaoke nights, campfires, games, or shared adventures, Jeff brought warmth, humor, and loyalty to the people he loved.

The outpouring of messages from friends, coworkers, and loved ones has been a testament to the impact he had on so many lives. Jeff was preparing to begin a new chapter as a husband, and his loved ones find comfort in knowing he spent his final days surrounded by love, anticipation, and hope for the future.

Celebrations of life have been planned to encourage all who loved Jeff to gather and share memories: July 18 at 6 p.m. at West Valley Bar & Grill in Yakima, Washington, and on August 2 at 2 p.m. at Sam Owens Campground in Hope, Idaho.

Jeff was deeply loved and will be missed beyond measure. Please honor him in whatever way feels true to how you knew him; do something he would enjoy, and be playful.