What is Superman's logo?

Answer 1

it is not really an s, it was an 8 like figure, but changed over the kryptonian years. is actually the symbol for the house of El on krypton. when Clark first found out he had super powers, he went hunting to find out everything about his kryptonian heritage. then he found out that the symbol for the house of El was that logo. that is why superman has an s on his chest. it is to keep his biological family alive close to his heart. it must have been very hard for Jerry siegal and Joe shuster to think of that shape, let alone make a story to it!

It really is a stylized number "8",incomplete in both loops,so it sort of resembles an "S";however,it stands for the house of El,and denotes a high rank in the Krypton science council.