The previous name
of John Clark
in the Tom Clancy book series
John Kelly served in Vietnam as a special forces operative, and later as an operative for the CIA. After an obvious breach of criminal law (after he becomes a vigilante when his girlfriend was killed by local drug lords) he takes his CIA Alias and becomes John Clark. (Without Remorse)
John Kelly, receives a Presidential Pardon for his crimes during the Ryan Administration.
Kelly, is strong, powerful, silent and deadly. You do not want to be his enemy.