Jack E. Threadgill, Sr. was born on July 29, 1930 in Carrollton where he graduated from Carrollton High School in 1947 and enrolled at West Georgia College. Threadgill left WGC to enlist in the United States Air Force where he served in Korea. Following his military service, Threadgill returned to Georgia where he completed a degree in accounting from Georgia State University in 1956. After earning his degree, he opened the first public CPA office in Carrollton in 1958. During his time in Carrollton, Threadgill served as the President of the Carrollton Jaycees from 1957-1965, as a Georgia House of Representatives member from 1967-1968, and as the Carroll County Tax Commissioner from 1993-1997. He was also a member of the Georgia Society of CPAs and received several service awards from this organization. Threadgill was also voted the Carrollton Outstanding Man of the Year in 1961. Threadgill taught at WGC as a temporary accounting instructor during the mid-1960s.

Threadgill was married twice; his first wife, Helen Chambers Threadgill, passed away in 1977 and he married his second wife Mary Gibson Threadgill in 1978. He had four children: Kathy, John, Jack, and Diane, as well as a stepson named Chris. Threadgill passed away on February 24, 2010.