Prince Charles of England was the intended victim of a botched assissination in 1994. In Austraila, Charles was about to start an awards-ceremony when David Kang leapt from the crowd and fired two shots at the Prince before he was subdued. The problem, other than aim, was that Kang fired his shots from a starting pistol, commonly used to signal the start of a race. Starting pistols fire blanks; he couldn't have hurt Prince Charles that way, let alone killed him.
There's video of the attempt here:
Also a video of comedian Eddie Izzard discussing the attempt (starts at 0:11-1:15):