The Batman hit the ball out of the park in its opening weekend, scoring a $128.5 million debut. The film is immensely popular among fans who've praised its style of being the most comic-book-accurate version of Batman audiences have seen on the big screen.
The desire for a sequel is there, and Warner Bros. will answer. But what which villains could stand up to the performance Paul Dano gave as The Riddler? Batman's rogues gallery is deep, as displayed by the Arkham video games and the animated series, which were the main inspirations for picks on a Reddit thread started by TheMonsterXzero54.
Poison Ivy
One character who fans haven't seen in live action since the cultural phenomenon of Batman and Robin is Poison Ivy. Played by actress Uma Thurman, the role was seen as goofy, along with the rest of the film.
The character has evolved a lot since the late '90s. As Redditor Alteronka says "Her motivation is so actual (global warming, etc.) so it will be nice." This would fit the grounded world of Reeves' world well, given that his first installment was already a film rich with metaphor.
Killer Croc
Killer Croc was a villain that gained a ton of popularity from the Arkham video games. Since he has not made an appearance in live action films, he would be a great choice for a sequel. Though he doesn't quite fit the world of Matt Reeves' non super-powered DC Universe, fans are hoping that the director will leave room for some absurdity.
Redditor Orycteropus-Afer sums up their desire for the character with "Arkham style horror esque killer croc where’s he’s like 8-10ft and an absolute monster but also sympathetic like he is in the Arkham games." If Matt Reeves is browsing Reddit, he'll have some great inspiration for his future sequels.
Scarecrow
Played by Peaky Blinders star Cillian Murphy in both Batman Begins and The Dark Knight Rises, Scarecrow took the back seat as a minor villain in these films. In terms of delving into psychological characters, like Reeves did in his first, Scarecrow fits the bill thematically for a sequel.
User No_Nectarine8102 says "Scarecrow, he is perfect because he uses fear just like Batman. Yet surprisingly, we have yet to have a good Scarecrow Vs Batman story." Maybe this won't be fitting with Batman's change of mindset to inspire hope at the end of The Batman, but seeing the character would still be exciting.
Man-Bat
Redditor Mountain_Chicken lists some of his desired antagonists, including Man-Bat, saying "It's a story about a dude who dresses up as a bat and grapples and glides around the city. It's okay to get bizarre. Why don't we tell a grounded story that embraces the weirdness of comic books?"
The comment was well upvoted by fans, as embracing the wackier characters is what makes Gotham, Gotham. Maybe it would take some time for matters to escalate to the level of Man-Bats and Killer Crocs, but fans aren't hoping to see this series concluded any time soon.
Phantasm
Batman: Mask of the Phantasm was referenced by Robert Pattinson as one of his main reference points for The Batman. The film is beloved by fans as a brilliant animated piece.The villain, Phantasm, though mostly known for the animated movie, made some appearances in the comics afterwards.
User Natural-Computer-3669 says "Mask of the Phantasm was my first Batman movie! It holds a special place in my heart." It would be exciting to see such an enigmatic character on the big screen. Phantasm is considered to be one of the best animated Batman movies.
Victor Zsasz
Zsasz appeared briefly in Batman Begins as an associate of Carmine Falcone. We never saw the character reach his true potential as Mr. Zsasz as he is in the comic books. Surely in a The Batman sequel, the character would be fully embraced, rather than being left as a glorified henchman.
Redditor celebfan01 says "Zasz could fit 8n with the tone, having posed bodies of his victims would be very creepy." If Reeves wanted to pursue another serial killer character, this could be a good way, especially as a minor villain for the film.
Hugo Strange
If fans enjoyed the cat and mouse game between Batman and The Riddler in The Batman, Hugo Strange is another character that could further engage Batman strategically.
"Strange can just goes full psychological. Exploring the mind of the bat. And why he is the way he is. He won't be full blown chaotic and bloody like Joker or Riddler" says user dadvader. Hugo could attempt to do what The Riddler failed at, in determining the true secret of Bruce Wayne and looking to expose it.
Black Mask
Fans suggested Black Mask on the thread in pairing with another character on this list. Similarly to how The Penguin served as a stature of organized crime in Gotham, Black Mask could take on a similar role. While Mr. Freeze could represent the side of Gotham that has been ruined by the corruption.
As Catwoman says in the movie, Gotham is up for grabs, with Falcone out of the way. Black Mask could be fun on his own as well, as proven by Ewan McGregor in Birds of Prey. CoraxtheRavenLord summarizes it perfectly, saying "Black Mask would be great for being the “face” of the new era of Gotham organized crime." Black Mask was also one of the best villains in the Arkham games series.
The Court of Owls
One of the newer villains in Batman's mythos is The Court of Owls, only recently appearing in The New 52 comics. This plotline has been praised by not only multitudes of fans, but also by Robert Pattinson himself, who theorized that this could be a path the films take.
Redditor Sly2855 says "Corruption seems to be a main theme here so maybe The Court of Owls." Given the historic nature of the Carmine Falcone/Wayne Family dynamic that The Batman explores, it would be interesting to further explore the deep roots of Gotham's corruption.
Mr. Freeze
The standout popular opinion for a villain who should appear in a sequel is Mr. Freeze. The character, portrayed to be extremely silly by Arnold Schwarzeneggar in Batman and Robin, is one of DC's most sympathetic villains. Batman: The Animated Series does the most justice to the character in on-screen attempts.
User Radgeta jokes "A live action tragic Mr. Freeze is needed, instead of Arnold spouting ice puns." Using Mr. Freeze as a villain would be a great way to show the effects of the corruption in Gotham on its people, with a character more sympathetic than The Riddler. An Easter Egg towards the end of the film even suggested at the character's existence.