William Clark Jarnagin (May 24, 1914 â October 19, 1979) was an American football and basketball coach. He served as the interim head football coach at HardinâÂÂSimmons University during the 1943 Sun Bowl. Jarnigan was the head football coach at West Texas State UniversityâÂÂnow known as West Texas A&M UniversityâÂÂfrom 1958 to 1959. He was also the head basketball coach at HardinâÂÂSimmons during the 1942âÂÂ43 season.