This is a fairly complicated bit of law… The long story short version is… "kinda".
Basically, the copyright itself can expire, but if the trade dress, iconic image, registered trademarks, etc are still in force/under separate copyright, then for the most part you're out of luck.
The most recent "superhero" to face this is probably still Popeye, whose original copyright expired in 2008/2009, at least throughout most of the world (I've given up on figuring out US copyright law, it's basically infinite for no good reason).
Popeye, as created and drawn by Elzie Seger, is totally fair game. You can whip up T-shirts of the image, re-release older strips, etc. Original narratives featuring the character, however, will probably have to duke it out with King Features, who hold the registered trademark for the image of Popeye. Since King Features is owned by the Hearst Corporation, well… I'm guessing it's not a legal battle many could afford to wage, let alone win.
The same would likely be true for any older heroes who still appear now and then in print (and in fact, when certain characters are about to become public domain, miraculously all the older books featuring them are re-released, with new covers, and perhaps even new stories, to help keep everything locked down).
The best thing to do, unfortunately, is simply to push forward with a totally original work… And if need be, use "similar archetypes" to replicate, parody, or otherwise make use of these older characters in ways that are both legally defensible, but also evocative and entertaining to prospective readers.
Good luck!
After the expiry of its copyright, can I use a comic character for my personal publishing?
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