The most obvious answer is that, no, Syfy's Krypton isn't part of the Arrowverse. After all, the so-called Superman prequel will debut in March on a different network, and take place (primarily, at least) in far-flung space, two generations before the events of Arrow, The Flash, Supergirl and DC's Legends of Tomorrow.
Produced by Warner Bros. Television and David S. Goyer's Phantom Four (not to be confused with Phantom Zone), Krypton isn't part of the Berlanti Productions network of DC Comics-inspired shows. However, we need only look to Constantine, which aired only briefly on NBC -- or even Supergirl, which began on CBS before making the move to The CW -- to find initially unrelated series that became fully integrated into Arrowverse continuity. (Matt Ryan, who reprised his role as magician John Constantine on Arrow, returns this season for a two-episode arc on Legends of Tomorrow before headlining his own animated series on CW Seed.)
While it seems highly unlikely we'll see any of the characters from Krypton, which centers on Superman's grandfather Seg-El, pay a visit to Central City or Star City, or board the Waverider, the show's connections to the Arrowverse, and the larger DC Universe, are unmistakable.
The most apparent link is, of course, that Krypton is the doomed homeworld of Supergirl (played on The CW by Melissa Benoist) and her cousin Superman (Tyler Hoechlin). And, as we see in the latest trailer, Superman and his legacy loom large over the upcoming series. Shaun Sipos guest stars as classic DC sci-fi adventurer Adam Strange, who travels back in time from Earth's present to Krypton's past to deliver a warning to young Seg-El (Cameron Cuffe), concerns about altering timelines be damned: "Someone from the future is coming to destroy Krypton, because where I'm from, you're grandson becomes the greatest hero of the universe."
That someone is the extraterrestrial android Brainiac (Blake Ritson), a classic Superman adversary who may have a tangential connection to Supergirl, which will introduce the Legion of Super-Heroes member Brainiac-5 in its Jan. 15 midseason premiere. In DC Comics, the character hails from the planet Colu, whose inhabitants claim descent from -- you guessed it! -- Brainiac.
What's more, Krypton's creators have teased an appearance by Hawkgirl who, as played by Ciara Renée, starred in the first season of Legends of Tomorrow. And, frankly, it sounds as if the new series could be more than a little similar to Legends.
“The deal with the show is it’s kind of this gateway into the DC science fiction universe,” Goyer explained during the Television Critics Association's winter press tour. “Because also the Phantom Zone figures into this show, it means we can delve into other times and planets eventually.”
Goyer and Geoff Johns, DC Entertainment's president and chief creative officer, have suggested a veritable who's who of the company's cosmic characters -- including the Green Lantern Corps and the Omega Men -- could make appearances on Krypton. "Yeah, if the fans have read it in Mystery in Space, it will probably end up in our show," Johns said. "We were talking about the Omega Men earlier. Any of these characters will eventually show up in Krypton."
None of that's to say Krypton is part of the Arrowverse, naturally. But it doesn't take much imagination to see how the events of Krypton's past could link to those of Supergirl's and Legends' present.
Debuting Wednesday, March 21, on Syfy, Krypton stars Cameron Cuffe, Georgina Campbell, Elliot Cowan, Ann Ogbomo, Rasmus Hardiker, Wallis Day, Aaron Pierre and Ian McElhinney.