Marvin was born December 2, 1937 to Raymond and Irene (Hohn) Koster. He married Darlene Weeks September 29, 1958. Marvin worked at Pete's Mileage in Sioux Falls, Farmers Produce, Kerr McGee/Derby Station, and 34 years with the Mitchell School District. He retired in 2012 due to his illness. Marvin cherished his family. He loved to ride motorcycle, fishing, and woodworking. He is survived by his wife Darlene of Stickney; sons Dennis (Kim) Koster of Rapid City, and Dan (Cindy) Koster of Stickney; 6 grandchildren; 2 step-grandsons; 4 great-grandchildren; A step-great-grandchild; sisters Alvina Johnson of Stoughton, WI and Stella (Jerome) Haiar, Mitchell, SD; and brother Larry Koster of Mitchell, SD. He was preceded in death by his parents; daughter Darlette Runestad; granddaughter Amie Jo Koster; brother Bernard; and sister Doris Jauert.