There are few prospects as interesting as secrets in comic books. Some things are kept secret from the people within the comic's world, like a superhero's secret identity, but the readers knew exactly who and what Peter Parker was in his very first appearance.
As a result, there aren't a lot of things that are kept a secret from fans, so to find them, you have to look into aspects of a character or comic book universe the creators might not have had an answer for from the beginning.
Other secrets could be planned from the very beginning, or develop over time as a result of popularity and reader interest.
Whatever the reason something is kept hidden when it does happen, the fans tend to appreciate the reveal, and it makes for a fantastic story. Imagine reading your favourite superhero character for years, only to learn they were something else all along.
You're either going to love it, or you'll hate it, but in all likelihood, you will still be fascinated by the secret reveal. Because comics are published monthly, it can take years for a story to develop into a secret revelation.
These secrets are some of the best, with creators keeping them from the fans for as long as was humanly possible.
10. The Secret Of Wonder Woman's Creator
Time To Discover: Sep/Oct '41 to Jun/Jul '42
Fans of Wonder Woman likely know that she was created by internationally games psychologist Dr. William Moulton Marston, the man who invented the polygraph. That's public information these days, but when Wonder Woman first appeared in All Star Comics #8 in 1941, the identity of her creator remained a mystery to the readers, and it would remain that way for quite a long time.
Wonder Woman was successful pretty much from the get-go, as she was a powerful female character introduced into a male-dominated media.
It didn't hurt that she was as beautiful as she was badass, and so it was natural that people wanted to know who was behind the impressive creation.
Interestingly, Marston's name was included on the first page of the book, but he was credited as one of several professionals as part of the "Editorial Advisory Board," and wasn't named as Wonder Woman's creator. Her intro story was credited to Charles Moulton, which just so happened to be the Doc's pen name.
In 1942, Wonder Woman became the first female superhero to get her own book, and with this milestone, Martson came out of the pseudonym closet. He dropped his pen name, and announced his work in a press release titled "Noted Psychologist Revealed as Author of Best-Selling 'Wonder Woman'."