"Perry Clark" is the alias adopted by an unknown expert assassin sent by NSA Officer Phillip Cowan to assassinate Michael Westen. The assassin impersonated the real Perry Clark; a CSS Bureaucrat, and contacted Michael under the pretense of holding a departmental review; which, if completely successfully, the recommendation would get him remove him off the Black List and revoke his Burn Notice.
Initially, the assassin tried to have Michael come to Fort Lauderdale for an appointment, arranging some things to ensure his death, but Michael, forbidden to travel, made him come to Miami. The assassin pretended to be a harried, hesitant and otherwise common desk-jockey, quickly gaining Michael's approval (having dealt with field operatives before, as well as the methods they employed to ascertain their authenticity); mostly due to Michael talking himself into denying his own instincts; wanting to resolve his burn notice. In truth, the assassin was cool, calming and good at killing people.
Eventually, one night, the assassin succeeded into getting into Michael's loft for a meeting. Michael, however, knew that the longer someone has been in the intelligence game, the more the person has to be careful about underestimating an opponent; in Michael's case; he does not think much of bureaucrats, feeling they're not worth his time or attention. As a result, a bureaucrat would be the perfect person to send to kill him. At the last second, Michael stopped the assassin from sneaking up on him and choking him with a garroting wire; concealed in his briefcase under a classified file. The two struggled, with Michael almost dying, but Michael, possessing the home-court advantage, punched open a nearby cupboard near him on the floor and, removing a hidden gun, successfully shot the assassin in the stomach. Giving up his attempt to kill him, the assassin staggered out the loft's door and vanished. The next morning; the Miami City Police Department found the assassin in an alley; he bled to death. There was no ID on him, and his fingerprints didn't show up in any government database, so, officially, he never existed.
Sam Axe was the first to theorize if the assassin was sent by Cowan, to which Michael admitted was "not a bad guess". Much later, Cowan, while meeting Michael and mere seconds before his own death, admitted to trying to have him killed.