Everyone knows that despite also being part of the DC Comics world, the likelihood of Batman ever showing up in the CW's Arrowverse is slim to none, partly because there's already a miniature Batman running around Gotham on Fox and a grown-up one starring in his own film franchise. Are these well-known superheroes too big for the small screen?
Maybe, but Supergirl had a couple Superman (Tyler Hoechlin) cameos last year and Oliver (Stephen Amell) literally just name-dropped Bruce Wayne on Arrow, so it's not out of this world crazy to wonder if the CW shows will ever bring another big name to Star City or Central City.
Actually, when you look back at it, The CW has played the Batman card more times than you might expect on its superhero shows. Here's a quick look at all the times Batman was mentioned one way or another in them.
Batman on The Flash
The first way The Flash started handing out subtle hints that Batman might be a thing in its universe was the newspaper clipping from the pilot episode. Your eye is naturally drawn to the headline, "Flash Missing, Vanishes in Crisis," but if you ever looked at the other stories on the page, you'd realize another, smaller headline reads, "Wayne Tech.-Queen Inc. Merger Complete."
That same headline changed to an announcement that the merger had fallen through when Barry (Grant Gustin) was in danger of changing the future.
Cisco (Carlos Valdes) has dropped a few Batman clues over the years, like calling Barry's burned alter ego "Two Face" and telling everyone he got the idea for the Flash Signal from a comic book.
Finally, when Barry travels to Earth 2 to assume the life of Barry Allen there, the contacts on his phone read Dad, Mom & Dad, Eddie, Bruce, Hal and Diana. Those last three should be familiar to Justice League fans as the secret identities of Batman, Green Lantern and Wonder Woman.
Batman on Arrow
The most obvious Batman allusion on Arrow was the inclusion of Ra's Al Ghul and the League of Assassins as a major part of the narrative. Additionally, countless other Batman villains like Deadshot, Huntress and even Harley Quinn have shown up on Arrow over the years.
Oliver also subtly mentioned Barbara Gordon (a.k.a Batgirl) in Season 4 when he considered making Felicity's (Emily Bett Rickards) codename Oracle, before finding out it was already taken. In the comics, Oracle was the hacker codename Barbara Gordon chose to go by after an injury turned her into a paraplegic.
Most recently, Oliver confirmed that Bruce Wayne is a character who lives in Gotham, but not that he was the caped crusader.
Batman on Supergirl
In the Season 2 premiere, a random citizen of National City can be heard saying, "That's it! We're moving back to Gotham," during an attack on the city. Not a clear Batman reference, sure, but it's at least a confirmation of his hometown.
Also in Season 2, Kara (Melissa Benoist) mentions that her cousin had previously worked with a vigilante before, but the partnership didn't seem like a smooth one. "Lots of gadgets. Lots of demons," she said. Sure, Superman could have made friends with another high-tech vigilante with tons of emotional drama... but probably not.
When you look at them all, these Batman mentions seem like they've been peppered in without much forethought to be simple easter eggs for DC fans. That's entirely possible given their random nature. However, there's also a chance that the Arrow, The Flash and Supergirl writers have been strategic about these mentions and what they mean for the Arrowverse narrative.
So far, there's been no sign that Batman exists on Earth 1 — Barry and Oliver's earth. Just because Bruce Wayne exists in that world, it's doesn't mean that he's dressing up as the caped crusader every night to keep Gotham safe. Why else would Oliver and Barry need to be fighting all of his villains? We also have to consider that if Cisco ripped off The Flash Signal from the Bat Signal based on a comic book, that Earth 1's version of Batman may be entirely fictional.
We've all but confirmed that he exists on Supergirl, thanks to Kara's clue about her cousin's gadget-happy vigilante partner, and unless Barry having the entire Justice League on speed dial in Earth 2 is just a coincidence, we can probably assume Batman exists there too.
But how likely are we to see him actually turn up on the CW? According to Marc Guggenheim, it's not impossible, but don't hold your breath.
The approval to incorporate Bruce Wayne and/or Batman actually doesn't come from The CW — it comes from DC Comics.
"A lot of times the conversation is, 'Hey we want to do this character' and DC's like 'No, we've got plans for that character in either this movie or TV show'," Guggenheim explained to Collider last month. "My attitude is, this is DC's toy box, they're just loaning us the toys, they're giving us permission to use their characters, but they are their characters. So it's like, OK."
With the Justice League film premiering later this year, it's probably safe to say that DC would prefer to keep one of their biggest superhero icons on reserve for the film franchise. And that's fine, since stepping on DC's toes is not a great way to collaborate, according to Guggenheim.
"[DC] are not only our partners, they've become my friends... and I want to be a respectful collaborator," he says.
So maybe we won't be seeing The CW's very own version of the Dark Knight, but we can still look forward to many more easter eggs about him.