The "S" is for super and the "U" is for unique… Oh. Wait. Nevermind. As the world's first superhero celebrates his 75th birthday, let's look back on the evolution of Superman. Click to see how his suit has changed over the years and view a Yahoo! Movies exclusive photo of Henry Cavill from this summer's "Man of Steel."

Superman's "S" didn't always fill his chest emblem. In Action Comics No. 1, published on April 18, 1938, Joe Shuster drew the insignia with a lot more yellow -- and the "S" wasn't all that fancy at first. Still, the template he and writer Jerry Siegel originated was quite impressive.

The Man of Steel grew into his more recognizable form in 1939 with his forelock of hair and bigger build in the character's first self-titled series. Still, his "S" logo was much smaller than what we're used to.

Starting in 1948, Kirk Alyn played the Man of Steel in a 15-episode live-action movie serial. He played Clark Kent and his high-belted superhero alter ego as two very distinct characters. Gotta love the tights and the Robin Hood-like lace-up boots!

George Reeves took over the role in June 1951 for the "Superman" television series. His look was a bit more polished than Alyn's, though he opted to play Clark Kent and his hero counterpart as more similar than his predecessor.

By 1971, Superman's muscles became more defined. That blue-and-red suit looks like a second skin.

When Christopher Reeve started portraying the Man of Steel in live action in 1978, his look was as similar as humanly possible to his comic counterpart -- down to the boots. His cape looked a bit longer, however. (And yeah, he probably would have had to juice up to get the muscle tone of the super-human illustrated version.)

Dean Cain played Superman alongside Teri Hatcher on television from 1993 to 1997 in "Lois & Clark: The New Adventures of Superman." His "S" logo was decidedly huge and his leotard had more shimmer to it than past heroic portrayals.

Alex Ross, who paints his comic book characters, started depicting Superman in 1993. He also made the emblem quite big and the man quite bulky.

Brandon Routh took on the infamous Man of Steel role in 2006's "Superman Returns." He sported a three dimensional insignia on his chest, lower-waisted trunks that resembled those of a swimmer, and a fancy schmancy belt that also donned the famed "S" logo.

Jim Lee started drawing a younger, more stylized, hulking Superman in 2010.

And now, let us introduce to you the Man of Steel himself, Henry Cavill. His suit has more texture and is fashioned after the modern comic book version Jim Lee has been drawing. Notice the darker blue color, the extra long cape, the textured surface, and -- look ma -- no trunks!
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