Tonight's episode of The Flash is expected to introduce the concept of Earth-2 to The CW's DC Universe -- err, Multiverse -- and with it, a man named Jay Garrick.
"My name is Jay Garrick," said the very first teaser for The Flash Season Two, "and your world is in danger."
Garrick was the original Flash in the comics. Created in 1940, Jay Garrick was the fastest man alive, until his comic was cancelled. When the character was reinvented during the Silver Age under famed editor Julius Schwartz, the concept was updated, including changing Garrick to Barry Allen.
A few years later, in The Flash#123, Garrick would team-up with Barry Allen, representing the introduction of DC's multiverse. It was revealed that almost every DC hero had an Earth-2 counterpart, usually Golden Age heroes with different civilian names and costumes, but similar codenames to characters who had been reinvented but occasionally -- as with Superman and Batman -- simply alternate-Earth versions of the same people.
There hasn't been a more-anticipated first appearance on The CW since Barry Allen popped up on Arrow, with fans eagerly anticipating Garrick's arrival since his helmet appeared toward the end of The Flash Season One's finale.
Shortly before that, series star Grant Gustin had said in an interview that he believed Earth-2 will be depicted on the show coming up and set photos had (accidentally?) revealed the Mercury-inspired helmet of Earth-2 Flash Jay Garrick near a Time Sphere being piloted by the Reverse Flash. During that same week during a Reddit AMA, series star Danielle Panabaker said that "I'm excited about the potential of Jay Garrick."
Prior to the Crisis on Infinite Earths, Garrick and the other Golden Age heroes were shunted off to Earth-2, so that their histories could remain intact but they could make way for younger versions to be the "main" heroes of the DC Universe, including new versions of characters like The Atom, as seen on Arrow and DC's Legends of Tomorrow.
Following the events of Crisis, the story in which Barry Allen died for a while, that alternate earth was one of the ones rolled into the main DC timeline, meaing that the heroes shared a single world and continuity, but that the Earth-2 heroes' adventures had happened primarily in the '40s and '50s, whereas the younger generation of heroes first appeared in the early '80s.
All of this was eventually reworked again by Flashpoint, which once again merged a number of worlds into a single timeline, but at the same time separated the Earth-2 heroes off onto their own corner of the multiverse again. Recent stories like The Multiversity and Convergence have featured the multiverse heavily.
There had been a previous Jay Garrick Easter egg -- "Garrick's Wharf" was a location in Keystone City when the Central City PD visited there -- but there has been no reference to a previous Flash, and since the Crisis hasn't happened yet on The Flash, and we know Teddy Sears's Jay Garrick is from Earth-2, it's likely safe to assume that Jay either doesn't exist on this Earth or is not a superhuman here if he does.
The season premiere of The Flash airs tonight at 8 p.m. ET/PT on The CW.