Johnny Gagnon is a minor character in killer7. Although he never appears onscreen, the killer7 intercepts a number of messages from him to someone called "Emir" (whom Garcian Smith later realises is his true identity), carried by carrier pigeon. Based on information gained from the memos, it seems that either the original, 13-year-old Emir hired Gagnon to gain information on the original killer7 as led by Harman and Dan Smith (unlikely given the reference to Samantha Sitbon and the fact that it was Yoon-Hyun who sold out the organization), or else that Emir's original persona quietly reasserted itself at some moment and then looked to Gagnon in an effort to reattempt its original goal.
Gagnon begins with a very cordial and business-like writing style in his messages, describing the information he has gained on each of the members with professionalism. He requests information on when and how he might receive his payment, but his employer is currently psychologically submerged, this never happens, though the killer7 continue to receive his memos. As the plot carries on, Gagnon becomes increasingly insistent regarding money, ultimately turning to threats, then becoming timid again and begging for even a portion of what he is owed. In the end, he writes off the job as an unfortunate loss and seems to give up, but one final note reveals that he had broken into Garcian's Trailerhouse and was waiting in ambush with a gun in the company of Harman and Samantha. However, Samantha found and killed him, then completed the transmission of his message, explaining the situation and signing it "Samantha Smith."
- Although unlikely, the nature of Gagnon's work makes it possible that he is a Searcher like Sumio Mondo.
- Each of the pigeons Johnny sends are named after James Bond characters.