William R. "Billy" Harrell was a professor of Agricultural Mechanization from 1969-2006.

Harrell earned degrees from Texas A&M University-Commerce (B.S. 1963; M.S. 1967) and the University of Missouri, Columbia (Ph.D. 1972), and later taught in Howe, Texas. He was active with local and area FFA and 4-H chapters as well as the North America Colleges and Teachers of Agriculture and Vocational Agriculture Teachers Association of Texas organizations.

He also served as Chair of the Department of Agriculture from September 1985 through August 1995.

In May 2011, the Board of Regents renamed the Agricultural Engineering Technology Center in his honor.