A couple of years ago I came across a fan sketch that John Romita did of Superman. I found this to be extremely fascinating and cool. Romita spent most of his professional career at Marvel Comics drawing Daredevil, Captain America, the Fantastic Four and most importantly, Spider-man.
Very early in his career he did work for DC Comics - the publishers of Superman - but most of his work for them was for their romance titles. He was not known for doing work on their super-heroes.
Above are my inks over his original pencils. I had to make a few corrections to Superman's uniform, as it would make sense he would not be familiar with the Man of Steel's outfit.
Below, I added color to the finished piece.