Jimmy Stewart
No it was Duke Wayne...Jimmy Stewart just got the credit for it...
Maybe we should ask him:
http://www.freerepublic.com/tag/by:libertyvalance/index?brevity=full;tab=comments
Hey Liberty! Who was it that shot you dead?
"You want me to spell it out for ya? Liberty Valance is the toughest man south of the Picketwire - next to me."