Ok, how about this for an idea. We take it in turns to post a favourite (British spelling) comic cover every day. This went really well on the comic fan website that I used to frequent. What we tried to do was find a theme or subject and follow that, until we all got bored with that theme. I'd like to propose a theme of letters of the alphabet. So, for the remainder of October (only 5 days) and all of November, we post comic cover pictures associated with the letter "A". Then in December, we post covers pertaining to the letter "B". The association to the letter can be as tenuous as you want it to be. For example I could post a cover from "Adventure Comics" or "Amazing Spider Man". However Spider Man covers can also be posted when we're on the letter "S". Adventure Comic covers could also be posted when we're on the letter "L" if they depict the Legion of Super Heroes. So, no real hard, fast rules - in fact the cleverer the interpretation of the letter, the better, as far as I'm concerned.
And it's not written in stone that we have to post a cover every day. There may be some days when no cover gets posted. There's nothing wrong with this, it just demonstrates that we all have lives to lead.
If everyone's in agreement I'd like to kick this off with one of my favourite Action Comic covers, from January 1967. Curt Swan really excelled himself here.
From the time of Metamorpho's introduction until the end of the Silver Age (1970/1971-ish) he was the most successful character that graduated to his own magazine or to a headlining spot (e.g., Enemy Ace in Star Spangled War Stories) after a stint in Showcase or The Brave and the Bold -- there is one exception. I'm defining success as number of issues of the character's own title. Also, I'm just counting the series that initially followed their stint; which would preclude a character such as the Spectre who has had many series over the years. Also, even though an issue featuring the Teen Titans appeared after Metamorpho's run in B&B, they had debuted earlier, so they don't count. The exception being The Phantom Stranger (or if we count post Silver Age [really Post Silver Age}, the Outsiders). Of course many of the later characters introduced in Showcase and B&B have been parts of the DC Universe for years (e.g., Dolphin, Johnny Double).
I guess one could argue that Binky had more post Showcase issues than Metamorpho but only if you add together Binky and Binky's Buddies.
That's not a very good batting average from late 1964, especially considering the earlier successes (e.g., The Flash, Challengers of the Unknown, Green Lantern, Atom, Justice League of America)
Did I overlook any series that was more successful than Metamorpho (and The Phantom Stranger)?
Binky was initially Leave it to Binky, so the GCD divides the run's issues between two galleries. The Leave it to Binky ones it places with the 1940s/50s issues. The combined Leave it to Binky/Binky run after the Showcase appearance was 21 issues. (That's not counting #82, which came out years later.)
The Silver Age Hawkman debuted in The Brave and the Bold #34(MAR61), a full year after the B&B debut of the Justice League. He did graduate to his own title after six tryout issues. His success has been an uphill battle, being more of a success in the JLA book than in solo appearances.
Superman’s Girlfriend Lois Lane debuted in Showcase #9(AUG57) right after Flash’s second tryout issue. Though not a new character, her title was around until 1974 when it was folded into The Superman Family.
Adam Strange debuted in Showcase #17(DEC58) and has been used ever since, though not as a big star.
The Metal Men debuted in Showcase #37(APR62). Their own title lasted from 1963 to 1978 and they have reappeared many times since then.
Then, of course, there was B'wana Beast….
Here is Will Eisner's most controversial cover. This is Wonder Comics #1 (May 1939), featuring the wonderful Wonder Man. Poor Wonder Man was destined never to see the light of day again, as, on March 15, 1939, DC Comics brought a copyright infringement lawsuit against Fox (the publisher), due to the character's similarities to Superman, as well as story and illustration elements that were similar to previous Superman adventures. The case was brought to court in Detective Comics, Inc. v. Bruns Publications, in which Eisner defended the originality of his creation. Despite this testimony, the subsequent decision forced Fox to drop the character after just one issue. This was the first copyright lawsuit in comic book history and set a precedent for DC Comics' vigorous protection of its characters.