Benjamin T. “Terry” Tonn passed away on August 24, 2026. He was born on April 17, 1937, in Sauk Centre, Minnesota, to Ben and Laura Tonn, joining his twin sisters Laura (“Tuck”) and Ann (“Nip”).

In 1949 the family moved from Minnesota to Superior. Terry graduated from Superior High School with the class of 1955. He earned a bachelor’s degree from the University of Wyoming and later received a master’s degree in science education from Antioch University in Ohio.

Terry married Marilyn Dee Pivik on April 12, 1958. They had five children: Lauri, Terry (“Tonto”), Mike, Lisa, and Leigh Ann. The couple later divorced. He subsequently married Jackie Sikowski; they had one son, Matt, and later divorced. In the early 1990s Terry met Jill Ost. They were married on April 24, 2001.

Terry taught school in Chugwater, Greybull, Lander, Chicago, and Casper. His final year of teaching was at East Junior High in Casper, where his favorite student that year later became his beloved daughter-in-law, Patti Sullivan Tonn. After leaving teaching, he pursued several business ventures, primarily in residential construction (including TNT Construction, Tonn Construction, and BLC) in Casper, Thermopolis, Dubois (where he met Jill), and Gillette.

Terry’s favorite pastimes were riding his horses in Wyoming’s mountains, hunting, fishing, and camping. He loved packing into the backcountry, often with his children, grandchildren, and friends. He and Jill spent many miles camping and hunting in the Wind River Mountains; his most treasured memories were the hunting trips up the South Fork of the Shoshone with his boys. He enjoyed good horses, campfires, his faithful Labrador retrievers, fresh trout, cold beers, and good whiskey. Terry had a great sense of humor, loved playing cribbage and poker, and traveling with Jill to visit friends and relatives across the West. Favorite traditions included Christmas Eve at the Tonnderosa barn and celebrating St. Patrick’s Day. He was a Life Member and Habitat Partner of the Rocky Mountain Elk Foundation and enjoyed attending its banquets.

Terry is survived by his wife Jill of Thermopolis, and his children: Lauri (Pat) Haid of Minnesota; Terry “Tonto” (Patti) Tonn of Thermopolis; Lisa (Sam) Saunders of Gillette; Leigh Ann (Jimmie Campbell) Yerkovich of Rock Springs; and Matt Tonn of Cheyenne; daughter-in-law Amie Tonn of Gillette; sister Laura (Tuck) Mills of Thermopolis and Minnesota; and sister-in-law Trudi Ost of Thermopolis.

He is also survived by his grandchildren: Aaron Haid, Joe Tonn, Jessica Ondler, Jake Tonn, Trisha Tonn, Penny Tonn, Ben Saunders, Madison Vandegrift, Luke Yerkovich, Abby DiGennaro, Bryce Tonn, and Ashleigh Tonn; and great-grandchildren Eliza, Violet, and James Haid; Ayden Saunders; Brooke and Logan Ondler; Jayme, Tynne, Gus, and Poppy Saunders; Vivi and Cooper Vandegrift; Cash Yerkovich; and two great-granddaughters expected in September. He is further survived by numerous beloved nieces, nephews, and their families.

Terry was preceded in death by his parents, Ben and Laura Tonn; sister Ann (“Nip”) Sani; son Mike Tonn; granddaughter Rachel Haid; and grandson Garret Saunders.

At his request, there will be no formal services. Instead, “one big party” is planned for Memorial Day 2027.

Donations in Terry’s memory may be made to Hot Springs County 4-H, 328 Arapahoe, Thermopolis, WY 82443.