Paul Leland Kirk (May 9, 1902 – June 5, 1970) was a chemist, forensic scientist and participant in the Manhattan Project who was specialized in microscopy. He also investigated the bedroom in which Sam Sheppard supposedly murdered his wife and provided the key blood spatter evidence that led to his acquittal in a retrial over 12 years after the murder. The highest honor one can receive in the criminalistics section of the American Academy of Forensic Sciences carries Kirk's name.