William Marshall Trimble, cofounder of Arlington College (now the University of Texas at Arlington), was born in Tarrant County, Texas, on June 1, 1867, to Green B. and Barbara Ann (Morrow) Trimble. He married Susan Catherine Borah of Grapevine on February 17, 1897; they had five children. After attending Bedford College in Bedford, Sam Houston State College in Huntsville, and Fort Worth University, Trimble graduated from North Texas Normal College (now the University of North Texas) at Denton in 1901 and Baylor University Medical School at Dallas in 1907. He taught at public schools in Huntsville, Mansfield, Bedford, and Arlington. While serving as coprincipal of the Arlington public schools with Lee M. Hammond in 1895, the two men led a campaign to establish Arlington College, a private institution, for which each personally donated five hundred dollars. Trimble and Hammond served as coprincipals of the new school until 1897. After leaving Arlington, Trimble taught in the public schools of Aledo and served as superintendent of the North Fort Worth public schools. Trimble received his medical degree and practiced medicine in Fort Worth from 1907 until 1922. He served for a time as city physician, in which position he promoted an improved program for cleanliness and sanitation. He was a member of the Tarrant County and Texas medical associations as well as the American Medical Association. He was a member of the Democratic party and the Church of Christ. He died on January 18, 1922, and is buried in Mount Olivet Cemetery, Fort Worth.