Welcome to The Hollywood Reporter's weekly DC TV Watch, a rundown of all things DC Comics on TV. Every Friday, we round up the major twists, epic fights, new mysteries and anything else that goes down on The CW's Arrow, The Flash, Legends of Tomorrow, Supergirl and Black Lightning and Fox's Gotham. While all the DC TV shows are on summer hiatus, THR breaks down all the latest news heading into their returns in the fall.

Supergirl

Another crossover? | Riverdale executive producer Roberto Aguirre-Sacasa set social media on fire late Wednesday when he tweeted a photo of Supergirl's Melissa Benoist in her full Supergirl costume on the Riverdale set, sitting in a booth at Pop's diner with stars Lili Reinhart and Camila Mendes. The three CW stars appeared to be shooting a wild crossover between the DC and the Archie drama. But unfortunately Aguirre-Sacasa's photo will have to be enough for die-hard viewers, as that was just a fun photo opp among friends taking a break between scenes on their respective shows (Supergirl and Riverdale's stages are next to one another in Vancouver). So while there's no news of a crossover between the two unlikely companions — for now — that's not to say it'd be a real stretch, given Riverdale (and Archie Comics) have been known to play around with characters like zombies, werewolves, witches and even the Punisher. So in the end, who knows? Maybe Supergirl could show up in Riverdale at some point in the future.

Gotham

Solomon Grundy's origins revealed | Gotham wasn't ready to say goodbye to Butch Gilzean (Drew Powell) in the finale last spring, and instead the DC Comics series surprised viewers by revealing his real name while he lay in a coma in the hospital: Cyrus Gold, aka iconic zombie supervillain Solomon Grundy. And while he won't be seen in the season-four premiere, executive producer John Stephens told EW that Butch's transformation into Solomon Grundy will happen quickly. "He's been in a vegetative state at Gotham General, and so in order to clear up space for more beds, the administrators at the hospital have him dumped in Slaughter Swamp, as one does in Gotham," said Stephens. "So he emerges reborn out of Slaughter Swamp as the character we know as Solomon Grundy [with no memory]. ... We begin the story of a very unlikely friendship between these two [Solomon and Ed Nygma, played by Cory Michael Smith] who are sworn enemies but now, all of a sudden in season four, are best friends as they move through Gotham."

The Flash and Arrow

Another crossover (for real this time!) | While Supergirl and Riverdale won't be crossing over anytime soon, The Flash and Arrow just set up another Arrow-verse crossover in an early episode of The Flash this season. Arrow's Felicity (Emily Bett Rickards) will take a little trip to Central City for "Girls Night Out," the fifth episode of season four. The episode will also include an appearance by Battlestar Galactica alum Katee Sackhoff as Amunet Black, the DC Comics villain Blacksmith. When the ladies of The Flash and Felicity take a break from being superheroes for a night out without the guys, they get into "trouble," and it sounds like Blacksmith will have a lot to do with that. She's described as "a steely and badass boss of an underground black market for supervillains," where she uses everything she has, including the long list of metahumans under her thumb, to make sure her criminal empire succeeds. Here's to hoping the ladies handle Blacksmith all on their own, without having to call on their male teammates for a superpowered assist because a little girl power is exactly what both shows need. This casting was first reported by EW.

What do you think of all the shocking twists and reveals from the DC Comics series? Let us know your thoughts in the comments section below.

Gotham returns for season four on Fox in the fall; Supergirl will return for season three on The CW in the fall; The Flash will return for season four on The CW in the fall; Arrow will return for season six on The CW in the fall; Legends of Tomorrow will return for season three on The CW in the fall; and Black Lightning will premiere midseason on The CW.