Gary James Lewingdon (born February 14, 1940 - October 24, 2004 in Columbus, Ohio) and Thaddeus Charles Lewingdon (born December 22, 1936 - April 16, 1989 in Pickaway County, Ohio) were American siblings and serial killers, who committed a series of ten murders in different Ohio counties from December 1977 and December 1978 for the motive of robbery.
As a murder weapon, the criminals used .22 caliber pistols, due to which they received the nickname "The .22 Caliber Killers".
In 1979, both brothers were sentenced to several terms of life imprisonment.