In my post chastising Time magazine for white-washing the extremism and intellectual dishonesty of Glenn Beck, I linked to a post by Eric Boehlert observing that the last time a president was hated this much by the "right-wing" a president was killed: JFK.
While that may be the case, it's also misleading, as JFK's killer, Lee Harvey Oswald, was not a "right-winger" but was instead a communist who had previously attempted to kill a member of the John Birch Society. (I'm not sure why this didn't occur to me at the time I posted it, but sure enough, it came to me while I was away from a computer.)
I have removed the link from that post and linked to this post as explanation.
For more on Oswald and his motivations, see here.