Dean LeRoy Sinclair, of Luverne, Minnesota, passed away on Friday, August 7, 2026, at the Minnesota Veterans Home in Luverne. He was 94 years old.

Dean LeRoy Sinclair was born on January 3, 1932, in Midland, Haakon County, South Dakota, to parents Herbert and Myra (Hill) Sinclair. He was a bright child and was homeschooled by his parents before attending formal school. As he reminisced about his childhood, he recounted moving several times and shared stories of notable events, including a time he saved someone from drowning while in a boat. He also recalled a boat ride that got out of control, where he had to hold on tightly to a rope and ride at the back of the boat, similar to how he had once ridden a team of horses while plowing fields. Despite facing significant challenges, including a battle with polio, Dean demonstrated remarkable resilience and learned to walk again. In a spontaneous moment at a track meet, he even jumped into a race and finished close to winning.

In 1954, Dean joined the United States Army during the Korean War and served as a radar repairman. Dean was honorably discharged in 1956. Shortly before or after basic training, he met Gertrude "Trudy" Huber. He enjoyed recalling the moment he first saw her coming down the stairs at the university, often mentioning how beautiful she looked. They later married and had three children: Sheryl, Mary, and Patty. He also had three grandchildren through Sheryl: Trudy Jean, Eric, and Vicki, as well as several great-grandchildren: Anna, Talis, Pamela, Daemon, James, Kolton, and Orion. He had one great-great-grandchild, Mikolai. Tragically, Trudy passed away in 1978 before she could meet all their children.

After Trudy's death, Dean entered a long-term relationship with Sharon Jones, which brought new friendships into his life, including those with Sharon's son, Shawn, and her friend's daughter, Deborah.

Throughout his life, Dean wore many hats. Dean pursued higher education and earned a PhD in Chemistry from Mount Marty College in Yankton, South Dakota. In addition to his military service, he worked as a college professor, high school teacher, Senate candidate for South Dakota, custodian, and even helped at a newspaper. One of his most notable achievements was writing over 14 books, including his theory on "Oscillator Substance in Existence" and various collections of poetry.

Dean had a fun-loving personality and enjoyed playing pranks and making puns. He delighted in surprising others, often dressing up in a werewolf mask and claws or wearing full COVID gear with only his eyes visible while walking around town or visiting the doctor's office. He loved eliciting reactions from people. One funny story he told was about going to a party with Trudy, where he drank non-alcoholic beverages and pretended to be drunk. This amused Trudy, especially when others insisted she drive home, and she remarked, "I'm the one that is drunk; he is the sober one."

He was a man of extremes; while some loved his personality and found him humorous, others disliked him for various reasons. Regardless of one's perception of him, Dean made a significant impact on many people's lives.

He is survived by his daughters, Patty (Clay) Halverson of Sioux Falls, Mary Sinclair of Chile, South America, and Sheryl Clyde-Schulte of Minneapolis, Minnesota. Dean is also survived by three grandchildren, Trudy Jean, Eric, and Vicki; seven great-grandchildren, Anna, Talis, Pamela, Daemon, James, Kolton, and Orion; and one great-great-grandchild, Mikolai.

Dean was preceded in death by his parents, Herbert and Myra Sinclair, as well as his wives, Gertrude "Trudy" and Sharon.

A memorial visitation will be held from 2:00 to 4:00 PM on Saturday, August 15, 2026 at Miller Funeral Home – downtown, 507 S. Main Avenue, Sioux Falls, SD 57104. Dean will be laid to rest at the Yankton Municipal Cemetery in Yankton, South Dakota.