In 1938, Jerry Siegel and Joel Shuster brought forth one of the most iconic characters to life in their publication of Action Comics #1. The character was not a bird, nor was it a plane, it was Superman! In this initial comic, the Man of Steel was only (yes, only) able to leap tall buildings, not defy the laws of gravity as we know him to today. Much like his abilities, the character himself has changed over the years, largely due to on-screen portrayals. The various actors who have taken on this role have big boots to fill, and each performance adds just a little bit more to the Man of Tomorrow.
Kirk Alyn
Kirk Alyn was the first actor to appear in a live-action format of Superman in 15-part serial in 1948. Being the first actor to assume this role, he was exactly as the comics had described Superman in those days; powerful yet careful. He showed the world what it would look like if a grown man wore pajamas and briefs, and somehow the world loved that.
George Reeves
Shortly after the run of the serials, George Reeves swooped in for The Adventures of Superman Television series, which began in black and white in 1952 and ended in full technicolor in 1958. This version brought color to the character in more than one way; the inescapable sense of confidence that Reeves exuded while acting as the Last Son of Krypton showed the audience that one man, albeit someone with power far beyond that of mortal men, could make a difference.
Christopher Reeve
If you've ever seen this performance, you understand why the tagline of Superman: The Movie (1978) was "you'll believe a man can fly." Christopher Reeve revolutionized the character by making it seem reasonable to believe that the nerdy guy at work could be catching planes falling out of the sky. Unlike his predecessors, Reeve separated Clark Kent and Superman into two distinct individuals, which made it a bit more understandable as to why Lois could never tell that the guy at the desk across from her was also the guy who stopped her from being a stain on the pavement because of a pair of Ray-Bans. He brought the concept of Superman to reality, even if he did it in a costume that screamed 1970's.
Dean Cain
You know that snack you want about midway between lunch and dinner? That was pretty much Dean Cain in Lois and Clark: The New Adventures of Superman. This version wasn't bad but it was just the 90's way of holding Superman fans over to the next main course. Also, as a side-note, Superman's eyes are blue; Dean Cain's are brown. Were colored contacts too much for the budget?
Tom Welling
Tom Welling and Smallville reminded Superman fans of one of his greatest features: he has the same problems as everyone else. Though the show didn't see him truly take flight until the last five minutes of the series finale, it also kept him metaphorically grounded. Superman is such a great hero because he can empathize with people since he shares in their struggles.
Brandon Routh
For Brandon Routh, see also Christopher Reeve. The 2006 movie Superman Returns gave the impression that it picked up somewhere after the events of the Christopher Reeve Superman movies. This only made it appropriate that Routh acted exactly as Reeve had done years before.
Henry Cavill
The thing no one asked themselves while watching Man of Steel or Batman v. Superman:Dawn of Justice was "does he even lift?" Henry Cavill's version of Superman was conceived by DC movie mogul Zack Snyder, who has said many times that his intent was to make these events reflect modern-day society as much as possible. If Superman can hold up a collapsing oil rig, it isn't unreasonable to think that he should be jacked. The darkness the Cavill portrays also demonstrate that a man with his own demons can be a symbol of hope.
If nothing else, these various renditions of the Man of Steel have made it obvious that no matter how we choose to do good in the world, and no matter what our strengths, we can all be a source of hope.