As mentioned in our new Captain Marvel review, Marv was created and published solely to secure Marvel Comics' trademark on the name "Captain Marvel." Neither Fawcett nor DC Comics had published a book called Captain Marvel for several years, so Marvel Comics jumped on it as soon as they could:
- Marv debuted in December, 1967, in Marvel Superheroes #12. This established the character, and tested the waters - if DC was going to complain, this was their chance.
- With (apparently) no one stopping them, Marvel gave Mar-Vell his own book in the first half of 1968. It never topped the sales charts, but it did manage to last until May of 1979 and gave us a spin-off character. The book was really limping along at the end, shipping only bi-monthly, at best. But DC had tried to revive Shazam by then, so Marvel kept the book going as long as they could.
- After stints in both the Defenders and the Avengers, Mar-Vell was featured in Marvel Comics' first original graphic novel, The Death of Captain Marvel in 1982.
- In 1985 there was a miniseries, The Life of Captain Marvel. It was mostly reprints, but it kept the trademark alive.
- Another "Captain Marvel" had been introduced in '82: Monica Rambeau, currently known as Nextwave's Pulsar. In 1989, she had her own one-shot, with the "Captain Marvel" name right across the top.
- Still using the Captain Marvel name, Monica had another one-shot in 1994.
- During 1993, Marvel introduced a new character in each title's Annual. "Legacy," the son of Mar-Vell, debuted in Silver Surfer Annual #6. By 1995, Genis-Vell had adopted his father's old codename, and had a short-lived ongoing series.
- Feeling the pinch, 1997 saw an Untold Tale of Captain Marvel.
- Genis was back in 2000 in a series written by Peter David. That one lasted, in one form or another, until 2004. Genis eventually took the name Photon and started showing up in Thunderbolts, while his sister Phyla-Vell became the fourth Captain Marvel.
So it's now been about three years since Marvel published a Captain Marvel title - that means they're almost due for a new one. Joe Quesada has said the new Captain Marvel is already kicking around the MU, but nobody's noticed yet. Whoever eventually comes down with the name, you should expect to see a comic with the title sometime in the near future - the biggest gap to date has been five years. Gotta protect those rights, after all.
One question about expies: How can Marvel Comics use obvious expies of Superman, i.e. Hyperion and Gladiator, without DC Comics suing them like they sued Fawcett Comics decades ago over The Big Red Cheese/Shazam/Billy Batson as Captain Marvel?
Probably because Marvel isn't trying to merchandise them the way Fawcett was: none of them have their own monthly comics or anything...
In the 1930's and 1940's, Superheroes were a brand-new thing, and Superman was the big money-maker for the company now known as DC. Anything that would threaten the uniqueness of the character, and thus draw readers away from him, was attacked by DC (Wonder man, Master Man, Captain Marvel, etc). By the 1970's, there were so many superheroes around, and Superman was no longer as unique as he used to me.
In the specific case of Hyperion, he was part of the Squadron Supreme, a super-team that was created as a spoof of DC's Justice League of America. Reportedly dC was supposed to make a spoof of the Aveners also, but never did.
Nowadays pastiche characters are pretty much accepted practice in the industry. So long as you don't swipe the name or costume, you can get away with it. Readers are sophisticated enough to know the difference between "Supreme" and Superman, and are unlikely to buy one thinking it's the other.
The mirror of that was that Fawcett was fully diversified as a publisher and had struck gold with Tom McCahill's new car road tests in Mechanix Illustrated starting in 1946.
When superheroes started to fade around 1950, it was easier to shut down their comics division (and DC was hungry for a juicy settlement being more dependent on superhero comic sales). The fact they'd have seemed like a passing fad at the time also explains why both companies, having spent a decade litigating over copyright, failed to take steps to maintain trademark.