It's a bird! It's a plane! It's a Jew?!
Superman sure doesn't look Jewish, what with the blue hair, perfect spitcurl and skintight underwear-on-the-outside couture. But take off those glasses and something looks fishy. And it ain't the creamed herring.
You see, both Supes' creators, Jerry Siegel and Joe Shuster, were Jews, giving him clearer Jewish parentage than half the people on this site. And Superman's story very much fits the Jewish immigrant experience of the 1930s.
His origins are dubious, so he disguises himself as a mild-mannered shmoe, unrecognizable to the world at large. He's just an everyday American. A little strange, sure, but no different than anyone else. But then, when the proper moment arrives, he whips off his disguise and reveals his true origins. He's a Jew!
Sound like someone familiar, Man of Steel?
Notice how his true identity gives him power? Even ultra-shiksa Lois Lane prefers the Mensch of Tomorrow to the white-bread-with-the-crusts-cut-off Clark Kent.
So why does he hide it? Maybe the Justice League has anti-semitic hiring policies. Who knows? So, until he comes out of the closet (or the phone booth, as is his wont), Superman's true identity remains in doubt.
But we know the truth and we're calling him out. Be proud of your Judaism, Superman! Give young Jewish geek-boys something better than a man made of rock to look up to.
And in return we promise not to tell Lex Luthor that your real weakness isn't kryptonite — just mayonnaise.