Needless to say, there were countless contributes to comic books throughout its lengthy history. However, a character known as Superman pioneered the industry by introducing the concept of a super hero in 1938. Since then, he had gone through many revisions, but none as significant as comic book writer and artist John Byrne.
After nearly 50 years, John Byrne was assigned to revamp the Superman series following his long running contributions at Marvel Comics. The timing was perfect as well, as Crisis on Infinite Earths just ended, which was a story that was meant for clarity and simplification of the DC universe (which is ironic in my opinion, because the story was confusing as hell). His major input was in the form of a mini-series called The Man of Steel. Luckily you can find this series in paperback on Amazon, (affiliate link) but due to a movie having the same name, it is often buried and hard to find.
So what did John Byrne, comic book artist and writer, change in Superman’s heritage? Very much, but not too much. I mean that in a good way. For starters, Clark Kent was not Superboy before coming Superman. He also has no Fortress of Solitude, and his adopted parents stay alive throughout his adult years. These decisions have created a permanent impact for future versions of Superman, however it might be more accurate to credit the Superman film with Christopher Reeves as influencing many of these decisions (minus the Fortress thing).
Another contribution from John Byrne was the now infamous friction between Batman and Superman (with no intention to undermine what Frank Miller provided in The Dark Knight Returns). For anyone who has been alive for the past 30 years or so and reads comic books, it should be clear that the rivalry between the two heroes is now a critical part of their relationship.
For those who are less familiar with the work of John Byrne, he contributed to a great little title called the How to Draw Comics Comic. Not only does it have a lot of interesting examples from a great artist, but apparently has many drawings from one of his sketchbooks that was stolen many years ago at a convention.