Gut-wrenching embarrassment.

Everybody loves Magneto.  He's universally recognized as the X-Men's greatest foe, even if he's a member sometimes.  He's in basically every X-themed cartoon and video game, he was played by Ian McKellen for three movies, and now he's killing Nazis and looking badass doing it in X-Men: First Class.  But before Chris Claremont revitalized him in the late '70s, he had some rough years.  He fought Captain America, and recruited a new highly-generic, albeit charmingly Jack Kirby-y, Brotherhood of Evil Mutants.  He fought the Defenders and turned into a baby.  He was in an incredibly embarrassing episode of the '70s Fantastic Four cartoon, where Reed Richards defeated him with a wooden gun.  Here's a taste:

And there's this, where Magneto's mad at a flunky, and...well, I'll let this panel speak for itself.

(Avengers #47, written by Roy Thomas, art by John Buscema and George Tuska)