Karen is a teacher working at Pembroke Day School for Girls.
Karen is busy grading papers with fellow teacher Elizabeth when a cold chill enters the room. Karen and Elizabeth try to close the windows and warm up the room, but to their horror, a hooded figure to appear and murder Karen.
To get rid of the ghost, Sam and Dean send Gavin MacLeod back in time to protect the ghost, Fiona Duncan, during her lifetime to prevent her from becoming vengeful. Gavin's sacrifice causes a new timeline, leading to a universe in which Karen was never killed.
- Karen was Fiona's last victim.