Villains have been on the rise in “Gotham” Season 2. Not only are they coming into the city, but some are rising from the grave. Episode 20 might have introduced a major living-dead bad guy from DC Comics, Solomon Grundy, whom Batman has battled before.

When Selina (Camren Bicondova) broke into Arkham Asylum and made her way to the Indian Hill facility, she started to hear and see horrific things in Strange’s (BD Wong) lab. While sneaking down a hallway, she came across a large man struggling with security guards. The man had glowing green eyes, scaly skin and grunted at the guards trying to move him. It was not clear who viewers were seeing in this scene. noted that Solomon Grundy is the likely villain briefly introduced. Because Strange has been bringing characters back from the dead, it would be fitting for him to have a part in the debut of the zombie supervillain. In the comics, Grundy came back from the dead after being killed and thrown in Slaughter Swamp. His body had been in the swamp for over 50 years before he came back to life as a big zombie-like creature.

There’s also a chance the character could have been Batman villain Killer Croc. The man had scaly skin and he looked green in the little amount of light that was placed on him. If the character on the show isn’t Killer Croc, fans will still see the villain on screen this year. Killer Croc (Adewale Akinnuoye-Agbaje) will be a part of “Suicide Squad,” which hits theaters on Aug. 5.

While the new villain could remain a mystery, we do know we’ll see some new and old baddies in episode 21 next week. Strange will bring Fish Mooney (Jada Pinkett Smith) back from the dead, and we expect to see more of the improved Firefly (Michelle Veintimilla). Photos for episode 21 also show a new experiment for Strange, which appears to be the creation of bad guy Clayface (Brian McManamon). 

Clayface Clayface (Brian McManamon) will be introduced in episode 21 of “Gotham” Season 2. Photo: Fox

Earlier this season, “Gotham” fans got a hint about which villains would return when Fish and Theo were both shown in containers of liquid in Strange’s lab. Both have since returned to the show to wreak havoc in the city. Jerome Valeska (Cameron Monaghan), who some believe could come back as the Joker, was also shown in a tank. However, Strange has yet to unleash Jerome back out into the world.

“Gotham” Season 2, episode 21, airs Monday, May 16, at 9 p.m. EDT on Fox. What villain do you believe Selina saw at Indian Hill? Sound off in the comments section below!