Lewis B. Allyn (Louis) (July 3, 1874[1] – May 7, 1940, in Westfield, Massachusetts) was an American chemistry professor and influential figure in the pure food movement at the time of his murder.

[2][3] He was teaching at Westfield Teachers College and contributing as a pure foods expert[4] for McClure's magazines at the time of his shooting.

According to Thomas F. Moriarty, the District Attorney at the time, a witness reported that she was parked 300 feet away when he was murdered.

[5] He said she recalled that "a man, wearing dark glasses with his coat collar pulled up was seated behind the wheel of the car," and that a black sedan was involved.

It was only three days after Professor Allyn's murder that Hitler began an invasion of the Netherlands, Belgium, and Luxembourg, ending the phoney war.