Ashton Kutcher as Superman
While Warner Bros. tried to push forward with Abrams and Ratner’s Superman, a cavalcade of well-known actors young, tall and dark-haired, put their hand up for the lead role. Among them were Brendan Fraser, David Boreanaz and Ashton Kutcher, who all auditioned.
Rumored to be the front-runner after a "very, very good" screen-test, Kutcher eventually ‘punk’d’ Ratner and producers when he decided to drop himself from the race, after being spooked by the alleged ‘Superman curse.'
"... I think there's a bit of a curse behind that role – the things that have happened to people. Also, I think once you've played that role then you're just forever known as Superman. It's kind of hard to play other things. I have a lot of other characters I'd rather play."
Ratner soon dropped out of the project too, leaving McG to jump back on board and pick up the Superman slack. Still using Abrams’ galaxy-spanning script, McG looked to cast an unknown as the Man of Steel, and shot test footage with TV stars Jason Behr (Roswell), Henry Cavill (The Tudors) and Jared Padalecki (Supernatural).
In the end, McG was spooked himself - not by the dreaded curse but by the flight to Australia, where Warner Bros. wanted, and eventually got, its new Superman film shot. Bryan Singer braved the travel, and with him came an adequate actor to fill the big red boots, Brandon Routh.
Sylvester Stallone as Superman
While Brandon Routh was a worthy replacement, Christopher Reeve was THE perfect Clark Kent/Superman, with producer Ilya Salkind fortunately taking the unknown actor route in order to cast his lead in his Superman: The Movie.
Directed by Richard Donner, Superman was the first big-budget, big-screen superhero movie and attracted some big names. The biggest - Warren Beatty, Robert Redford and Burt Reynolds - were said to have knocked back offers to star as Superman early on in development; but rising stars were knocking down Salkind's door to audition. They included Arnold Schwarzenegger, Nick Nolte and Sylvester Stallone, who threw his hat into the ring after the success of Rocky.
Stallone apparently lobbied hard for the part and could’ve been Superman - until he received a big right hook from Marlon Brando, who had already been signed to star as Jor-El, the father of Kal-El/Clark Kent/Superman. Brando didn't want the Itallion Stallion playing his son.
Salkind - the man who first gave Superman cinematic life and ultimately ended it with Superman III and IV - said just last month at the Wizard World Anaheim Comic Con that it would have been "a little bit difficult to imagine" Stallone in the role:
“After meeting a lot of actors, such as Jon Voight - we even met Neil Diamond, don’t ask me why - I knew in my heart of hearts it had to be an unknown.”
Thank god his heart of hearts was making the decision - the world would be a much sadder place if it had never known Reeves as the Man of Steel.