Johnny Campbell was a hunter, and related to Sam and Dean's mother, Mary's, side of the family.
When Dean was attacked by a Djinn, Sam rescued him and revealed he had been back from Hell for a year and hunting with cousins Gwen Campbell, Christian Campbell, Mark Campbell and grandfather Samuel Campbell.
To ensure that the Braedens, Lisa and Ben, were safe from the djinns currently attacking the hunters, Samuel had sent John to watch over the pair and their home.
Unfortunately for Johnny, he was killed by a Djinn while still sitting inside his car. Dean rushed back to the house soon after and relocates the pair to Bobby's house.
- Actor Brendon Zub also portrayed a cook in the season 9 episode "The Purge".
- Johnny is the first known Campbell to die since Mary herself in 1983.
- It is never revealed what kind of relation Johnny had to the other members other than being a member of the same family.