The CW’s DC TV crossovers need a major villain to fight. Last year, Nazi’s from Earth X were an issue. The year before that, aliens called the Dominators were invading. This time, however, it’s Gotham City baddies that bring the heroes together.

Dr. John Deegan will be a 2018 Arrowverse crossover villain. Entertainment Weekly reports that Jeremy Davies, who won an Emmy for his role on “Justified” in 2012, will play the doctor. Though he works at the Arkham Asylum for the Criminally Insane, he might be causing more trouble than the patients.

He’ll be part of the reason the Green Arrow/Oliver Queen (Stephen Amell), The Flash/Barry Allen (Grant Gustin) and Supergirl/Kara Danvers (Melissa Benoist) are drawn to Gotham, but he isn’t the only villain in town. Nora Fries (Cassandra Jean Amell, wife of Stephen Amell), the wife of Mr. Freeze, will be making an appearance as well. Her icy husband, however, will not, according to TVLine.

Jeremy Davies
Jeremy Davies will play an unstable doctor at Arkham Asylum in the Arrowverse crossover. He is pictured with his Emmy for best guest actor on a drama on Sept. 23, 2012 in Los Angeles. Frederick M. Brown/Getty Images

Whatever his plans are, they’re likely very attention-grabbing. After all, our heroes are on different Earths. Kara is on Earth 38, while Barry and Oliver are on Earth One. So which Earth is home to Gotham and Arkham Asylum?

Not much has been revealed about the Arrowverse crossover yet, so it isn’t clear which Earth it will take place on. However, it does seem like Supergirl will have a few friends around. Her cousin Superman/Clark Kent (Tyler Hoechlin) will be around for this team-up, and Lois Lane (Elizabeth Tulloch) will be introduced in the episode as well. Though previous team-ups with Green Arrow have put Supergirl on Earth One, it’s possible this one could take place on her Earth.

Wherever they are, they’ll have help from a new hero. Ruby Rose will play Batwoman/Kate Kane, a lesbian superhero, in the winter TV event. The casting news wasn’t without backlash. Rose quit social media shortly after she was announced as the character.

Arrowverse crossover spoilers
The Arrowverse crossover will bring together loads of superheroes. The 2016 event is pictured above. Bettina Strauss/The CW

Batwoman likely won’t disappear after the crossover event, though. Greg Berlanti, the producer behind all of the DC TV shows on The CW, is developing a spinoff series for her with showrunner Caroline Dries.

While it may seem like the Arrowverse crossover is jam-packed, remember that the CW is actually limiting the number of heroes involved. The Legends of Tomorrow aren’t going to make an appearance this year, and “Black Lightning” still hasn’t been connected to the Arrowverse (yet).

The three-night Arrowverse kicks off Sunday, Dec. 9 on The CW.