John Jacob Abt (May 1, 1904 – August 10, 1991) was an American lawyer and politician, who spent most of his career as chief counsel to the Communist Party USA (CPUSA) and was accused of membership in the Communist Party and the "Ware Group" alleged by Whittaker Chambers to be a Soviet spy network.
Abt denied that the group was a spy ring, noting that the security classification system did not yet exist, and none of the documents he had access to involved national security.