Dennis was born September 4, 1947 in Winnebago, Nebraska the son of Isaac and Ada (Johnson) Red Owl. He grew up in South Sioux, graduating from South Sioux City High School. Dennis continued his education at Western Iowa Tech.
Dennis met Debra Trudell in 1983. Together they made their home in Sioux City before moving to Lincoln in 1989. Over the years, Dennis worked at Meadow Gold Dairy until his retirement. He enjoyed exercising, arts and crafts, and was a Corn Husker fan.
Survivors include his wife, Debbie of Lincoln, Ne; 3 children, Carlos Castillo, Ricky Castillo III, and Denise Heinemann; several grandchildren; 1 great-grandchild; a sister, Alice Faye Rouillard of Santee, Ne., and 2 brothers, Robert Red Owl and Ronald Red Owl, both of Sioux City.
He was preceded in death by his parents; 1 sister and 6 brothers.