The Butler Act was a 1925 Tennessee law prohibiting public school teachers from denying the Biblical account of mankind's origin. The law also prevented the teaching of the evolution of man from what it referred to as lower orders of animals in place of the Biblical account. The law was introduced by Tennessee House of Representatives member John Washington Butler, from whom the law got its name. It was enacted as Tennessee Code Annotated Title 49 (Education) Section 1922, having been signed into law by Tennessee governor Austin Peay.

The law was challenged later that year in a famous trial in Dayton, Tennessee called the Scopes Trial which included a raucous confrontation between prosecution attorney and fundamentalist religious leader, William Jennings Bryan, and noted defense attorney and religious agnostic, Clarence Darrow.

It was repealed in 1967.