|Dates||May 18, 2017 (born)|
|Location||North Cove, Washington|
|Episode(s)||12.23 All Along the Watchtower|
Jack is the Nephilim son of Kelly Kline and Lucifer. He was conceived when Lucifer inhabited the body of President Jefferson Rooney, with whom Kelly was having a relationship. Angels believe that Nephilim are abominations that can destroy worlds; with Jack being the son of Lucifer, it is believed he will also be a force of great evil. However, after the Nephilim, while in utero, gives Castiel a glimpse of the future, Castiel believes Jack will bring peace and paradise to Earth.
While Sam, Dean, and Castiel deal with Lucifer, Kelly Kline finally gives birth to Jack in an explosion of light that renders Mary unconscious. When Sam notices the light coming from the home, he goes to check on Kelly, only to find her lying dead in her bed. When he hears a noise, he goes to investigate. He notices footprints leading to Jack's nursery, where he finds an already adult-looking Jack huddled in the corner, smiling as his eyes glow gold.