Penguin (Robin Lord Taylor) and Edward Nygma a.k.a. the Riddler (Cory Michael Smith) met briefly on Fox's "Gotham" during Season 1, but the two villains were brought together once again. On Season 2, episode 9, Nygma helped Penguin return to being the crime boss and killer that he is, while Penguin agreed to give Nygma a few evil pointers. 

The two have gone on to become good friends who sing, eat dinner, and kill together. It's unclear how much more the two will collaborate on the show, but this isn't the first time Batman villains have joined forces on screen. 

Here are four other times the Caped Crusader's nemeses have come together to try and stop the Dark Knight.

1. Catwoman and Penguin in "Batman Returns" (1992)

In Tim Burton's first Batman film Jack Nicholson carried the torch as the lone villain against Batman (Michael Keaton). For the sequel, Burton decided the more the merrier and added both Penguin (Danny DeVito) and Catwoman (Michelle Pfeiffer) for "Batman Returns," which set forth a pattern in several of the Batman movies that followed. Although they are enemies at first, Penguin and Catwoman found common ground with their mutual hate for Batman. However, a relationship with Bruce Wayne caused a few problems for their partnership.

2. The Riddler and Two-Face in "Batman Forever" (1995)

The desire to get rid of Batman (Val Kilmer) and take control of Gotham City was enough to get Two-Face (Tommy Lee Jones) to put aside his rage and team up with the wacky Riddler (Jim Carrey). Director Joel Schumacher took over for Burton, which took the Batman films in a new direction where the villains were seen more as more funny than intimidating.

3. Mr. Freeze and Poison Ivy in "Batman & Robin" (1997)

Not one of the best Batman films, but the teaming of Mr. Freeze (Arnold Schwarzenegger) and Poison Ivy (Uma Thurman) was an interesting choice. The two come together after Poison Ivy broke Freeze out of Arkham Asylum and wanted to come together to execute a plan of wiping out all of humanity and giving her plants their own world to live in. Bane, the villain made famous by Christopher Nolan's "The Dark Knight Rises," also appears in the film as a huge henchman for Poison Ivy.

4. The Joker and Two-Face in "The Dark Knight" (2008)

Althought the two villains didn't officially join forces, the Joker (Health Ledger) set Harvey Dent (Aaron Eckhart) on his way to the dark side as Two-Face in "The Dark Knight." The Joker visited Dent in the hospital to tell him that what happened with Rachel (Maggie Gyllenhaal) wasn't anything personal and that Dent should now introduce "a little chaos" into his life. Batman now has to not only find a way to stop the Joker, but also a revenge-seeking Dent.

Watch Penguin and Nygma's new partnership unfold on "Gotham" Mondays at 8 p.m. EST on Fox.