And that's the third one. The JLA first appeared in The Brave and the Bold #28, cover dated February-March 1960; Green Lantern #1 didn't come out until almost six months later.

Your question, JTR.

Really? Wow. I had thought that WW was a casualty of the Frederic Wertham era.

--thanks, you learn something new every day.
wyld

She was one of the few that weren't. Superman, Batman, Wonder Woman, and Superboy had their titles continuously published through the 50s; Golden-Age back-up features Aquaman and Green Arrow hung on too, as back-ups in those characters' books. (A few other 1940s back-ups survived into the 50s, like Shining Knight, Johnny Quick, and Robotman; but one by one they vanished, leaving only Aquaman and Green Arrow continuing through the 50s and into the 60s, which is why those two eventually became part of the JLA.)

Superman's a little easier; in the late 50s they start bringing in characters and concepts unique to Earth-One, like Supergirl, Brainiac, and the Bottle City of Kandor.

Green Arrow and Aquaman, of course, got completely new origin stories in 1959, vastly different from their Golden-Age origins.

But Batman sticks out. Even after it had been "defined" as two different "Batman's", one would often make referances to the other's adventures, tho they shouldn't of known of them. Weird stuff.

And I'm still stuck for a new question. Hmm...

Bill Jensen killed whom?

Commissioner Bruce Wayne, aka Batman of Earth-Two

You are correct.

And he had nothing to do with the death of Kathy Dare.

Name someone who has used two different super-heroic identities, both of which were first used by someone else during the 1940s.

Jason Todd

Not Jason, no. The Red Hood was neither a super-hero, nor did he appear in the 1940s (that classic Batman story was published in 1950).

I will give the hint that the two originators of the heroic identities were both JSA members. (And by "originators" I mean they were the first people published in comics to use these identities, later retcons notwithstanding.)