Let's talk a second about Public Domain Characters and Golden Age Comics. So does Pierre. The guy over to the left here is the Gray Ghost, the first Golden Age character he ever drew for the Flashback Universe. At the time I wasn't sure I wanted a Golden Age Flashback Universe, but I'll show you how the character AND the FBU idea evolved in a second.
First let me answer a reader's email:
Where can I find a list of all the Public Domain Superheroes?
Wikipedia used to be a great source for a complete list of all public domain comic books characters, but as with all useful wiki pages, some jackass put  on the page, and now it's gone.
Now the best place to start is the Golden Age Comic Book site:
For characters outside of comics, you can begin here: the index of Public Domain Resources note: Wikipedia has a similar index on this page: Wiki: Public Domain Resource but it's rather long and hard to wade through, and it might be gone next week, so I wouldn't depend on it.
This is such a confusing issue partly because American Copyright law is a mish mosh that changes depending on the time a character was created AND because it's hard to verify exactly whether companies really took the time to copyright/trademark their characters correctly the first time.
Witness this discussion at Wikipedia over the Nedor Superheroes:
...The above report on Nedor characters may or may not be accurate depending on the actual circumstances of the company when it ceased publishing. It is clear that Ned Pines did renew copyright on most of his characters' first appearances, despite widely reported statements to the contrary. Also, Pines sold one of his companies, Popular Library, to Fawcett Publishing, who in turn, sold it to CBS, and today, the Nedor characters would be owned by either Bertelsman AG or Warner, if the comic books they appeared in were published by Popular Library. If Ned Pines used different companies to publish these books, they may be in public domain.
So, given all that, when Pierre came to me with an idea of working on some Public Domain heroes into our Flashback Universe, I was a little hesitant.
First, how would we know if they were really public domain?
Second, I've heard that even if you use public domain characters, it's hard to then turn around and do anything else with them (like a movie for instance) because other companies are scared of public domain characters.
Still, I liked the idea of working in the Golden Age setting, so we decided to create our OWN Golden Age universe, which we smartly dubbed the WayBack Universe.
The first stab at this was to create a super group of characters similar to the Invaders. If you've read the Paladin comic, you've already seen a reference to these characters. In that comic we call them the Intruders, but in other places, they have been called the Insurgents. I'm going to say that because their missions were classified by the government, an *official* name was never recommended. ;)
One of the coolest characters in that group is the Golden Age WildCard:
Another favorite of mine is the Crimson Cossack (there's a big story behind this pose that I won't go into here...)
Not seen in the Intruders picture is probably one of my favorite WayBack characters - a character who sort of started as the Gray Ghost and changed into something much cooler I think - The Purple Puma.
And of course heroes are only as good as the villains they face, so we've created quite a few WayBack Universe Villains as well...here is a group we call the U-Bolts.
And here is a another group shot with a few familiar faces in the mix...click to enlargify.
We have several more characters, and hope to have a complete comic featuring some of them in the near future. (I just need a story... :D )
I'll keep you posted. :)