10. Superman - Whatever Happened To The Man Of Tomorrow?
Throughout Superman's run in comics, we've seen pretty much every colour of Kryptonite under the rainbow used against the Man of Steel. What we haven't often seen, however, is golden Kryptonite, which was introduced in Adventure Comics #299, and then ignored for years until it showed up for the dramatic closing scenes of Superman: Whatever Happened To The Man of Tomorrow?
After a series of intense battles with all of his oldest foes, Clark kills Mr. Mxyzptlk, and is then struck with horror at having purposefully and brutally murdered the dimension-hopping alien.
Consumed with regret, the hero enacts the plan he had created in event of him ever using his powers for wrongdoing, stepping into the golden Kryptonite chamber that permanently removes all of the DC titan's powers from him.
With so much of the comic suggesting that Superman would die at the end, it's strangely rewarding to see him actually only lose his powers, and go on to live a happy life with his wife and child.