The character of John Witter, played by Joe Don Baker in the original 1973 film, was fictional.
However, the movie was inspired by the true story of Buford Pusser, a real-life sheriff from McNairy County, Tennessee. He was known for his tough stance against crime and corruption, and he often carried a billy club to enforce the law.
Pusser's story was the inspiration for the "Walking Tall" franchise, but the character of John Witter was a fictionalized version of him.