John Quinn on Day 7
|Portrayed by||Sebastian Roche|
|Last appearance||Day 7: 9:00 PM – 10:00 PM|
Quinn, along with his partner, Halcott, were sent to the apartment of Chris Whitley by Jonas Hodges to retrieve the files which implicated Nichols in his arms dealings with Benjamin Juma. After Chris arrived home, Quinn and Halcott held him down while the two administered a drug to him, hoping to pry any more information out of Chris.
After feeling satisfied that Hodges and Nichols were in the clear, Quinn and Halcott were ordered to kill Whitley and dispose of his body. During the Inauguration ceremony for Allison Taylor, the two hitmen are shown burying Chris' body underground beneath some cement.
 Day 7
Quinn is sent by Greg Seaton to kill off Ryan Burnett at a local hospital before Jack Bauer arrives there to interrogate him on what he knows about a future threat within the country. Once at the hospital, Quinn disguises himself as an orderly and sneaks into the room of an elderly patient. He then uses a pillow to suffocate the man, causing nurses to rush into the room after noticing that the patient flat-lined. Using this as a distraction, Quinn makes his way to the nurse’s station and downloads schematics for the building into his PDA. Locating Burnett’s room, Quinn goes into a nearby supply room and opens up the ceiling, lifting himself into the air duct.
Maneuvering his way through the ceiling, Quinn finally arrives at Burnett’s room. Just as Jack is about to get information out of Burnett, Quinn drops a metallic object down into the room, releasing a nerve agent that paralyzes Jack. Wearing a gas mask, Quinn lowers himself into the room and uses a piece of broken glass to cut the throat of Burnett, killing him. With his plan of framing Jack for the murder of Burnett complete, Quinn goes back up into the air duct and eventually makes his way out of the building.
While driving away from the hospital, Quinn hears over FBI communications that Jack was able to escape the hospital. He calls Greg Seaton and tells him of Bauer being on the run, but that he was able to kill Burnett. Later on, Quinn arrives at the residence of Senator Mayer. Disguising himself as metro police, Quinn guns down Mayer with a pistol. He then gives chase to Jack, shooting him in the arm as he runs away. Following the blood trail to a nearby construction yard, Quinn enters a trailer that has a door handle covered in blood. After shooting up the room, Quinn is knocked over as Jack uses a bulldozer to tip the trailer on its side.
Escaping out the top of the trailer, Quinn is tackled to the ground by Jack. Quinn picks up a crowbar and tries to hit Jack, but misses with the weapon. Following more hand-to-hand fighting between the two, Jack picks up a screwdriver from the ground and throws it at Quinn, lodging the tool in his chest. Jack then grabs a piece of wood and strikes Quinn, knocking him to the ground. Bleeding to death, Quinn is asked when the weapons will be arriving, and he tells Jack that they are already there. Quinn would then die seconds later.