Jumper Wiki
Griffin's friend
Biographical Information
Name Unknown
Gender Male
Status Deceased
Affiliation Jumpers
Physical Description
Behind the Scenes

Griffin O'Conner: "Actually, I knew this Jumper once--crazy bastard --tried to hop a whole building. Won't be trying that again."
David Rice: "Why's that?"
Griffin O'Conner: "That's 'cause he's dead. Killed him. Still managed to shake it a little though."
Griffin O'Conner to David Rice[src]

This unnamed Jumper was a man who was once friends with Griffin before his death. His real name is never given nor the location, but Griffin tells a story. This Jumper tried jumping a whole building which killed him. The pressure of the weight of the building probably killed him or the strain of trying to jump something that heavy. This is an indication that, just like exercise, to mentally jump something heavy requires training.