Batman is one of the most recognizable faces in pop culture, but his younger years prior to becoming a crime-fighter have rarely been explored in comics, TV series or films. That changed in 2014, when Gotham, a prequel series centered around Bruce Wayne's home city before the arrival of the Dark Knight, came around. Given Batman's absence from the show, a lot of people wondered whether Gotham had a future. Now, four years after its debut, the series continues going strong.

Creating a prequel show based around a mythology as beloved as Batman's isn't easy, especially when the Caped Crusader himself is off-limits to use in the narrative. Because of that, the minds behind the series have had to offer their own take on the franchise, one that's strong enough to stand apart from the comic book source material. In only four seasons, the show has drastically changed the Batman mythology. Most of the changes have most likely gone unnoticed by non comic-book reading viewers. Hardcore fans, however, have certainly noticed them. If you want to get an idea of just how much the series has altered the Caped Crusader's world, here are 15 massive changes Gotham's made to the Batman mythos.

15 IVY PEPPER BECOMING POISON IVY

Pamela Isley, aka Poison Ivy, is one of Batman's most popular foes. Despite her popularity, however, she was given a complete makeover for Gotham. The show turned Pamela into Ivy Pepper, the daughter of a man who was framed for the Wayne murders. The girl eventually became an orphan, and she decided to live on the streets. Unfortunately for her, living on her own didn't end well.

Ivy was turned into an adult by another villain with age-altering powers, and she started using plant-based potions to control people into doing her bidding.

As dedicated comic book readers will know. that's quite a departure from the original Poison Ivy. Ultimately, aside from her green color scheme and undying love of nature, the character's two versions have almost nothing in common. Still, who knows? Perhaps the show will explore a more comic-accurate Ivy down the line.

14 LESLIE THOMPKINS AND JIM GORDON'S ROMANCE

Following his disastrous split from Barbara Kean, Jim Gordon found love once again with Leslie Thompkins, a talented medical examiner for the GCPD. While a bit rocky at times, their relationship has consistently captivated viewers, and it's inadvertently become an integral part of the series. Given the popularity of their romance, casual viewers may be surprised to know that Leslie and Jim were never an item in the comics.

On the contrary. On the printed page, the two characters were completely unrelated to each other, and their love lives were vastly different. Jim, as mentioned, was married to Barbara Kean, while Leslie became romantically involved with Alfred Pennyworth in a few occasions. It's unclear whether Thompkins and Gordon's relationship will continue in Gotham, but going by how the series is shaping up, they seem to have a bright future ahead of themselves.

13 COPPERHEAD

In season one, Gotham introduced Larissa Diaz, aka Copperhead, a mercenary who was hired to kill Bruce Wayne and Selina Kyle. There have been various individuals who've taken up the Copperhead moniker throughout the years in the comic book world (five, to be precise), but Gotham's interpretation of the character, aside from her contortionist abilities, had pretty much nothing to do with any of them.

Most of the people who've taken up the Copperhead identity in the comics, for example, have used a high-tech suit of armor and a variety of poisons to perform their villainous deeds.

Gotham ditched those elements for Diaz, opting to make her a more grounded character. Fortunately, that approach paid off, because despite her brief appearance, she became one of the show's most memorable baddies. She was ruthless, powerful, and overall felt like an actual threat to Jim Gordon and his allies.

12 MR. FREEZE'S BACKSTORY

Gotham introduced Victor Fries during its second season. At first, the show seemed to remain fairly faithful to the character's backstory, portraying him as a brilliant scientist desperate to save his wife, Nora, from a mysterious disease. From then on, though, the people behind the series decided to take a different path with the scientist. Unlike the comics, he became a super villain way before suffering the cryogenic accident that turned him into Mr. Freeze.

In the show, Fries made a habit out of cryogenically freezing people around Gotham to later experiment on them, looking for the safest method to put his wife in suspended animation. Disturbingly, he showed no remorse when killing his subjects, and was simply focused on moving on to his next experiment. Because of that, his eventual turn into Mr. Freeze didn't mark a significant shift for him.

11 TOMMY ELLIOT'S DYNAMIC WITH BRUCE WAYNE

Batman has a lot of enemies, but very few are as emotionally connected to him as Tommy Elliot. In the comics, Elliot and Wayne grew up together and became good friends. Sadly, their friendship fell apart when Tommy tried to kill his parents. While his father died, Thomas Wayne managed to save his mother, and that caused Elliot to harbor a deep hatred for Bruce.

This resentment eventually led him to become the villain known as Hush.

Gotham gave this dynamic a drastic spin. Following his parents' murder, Bruce went back to school. There, he encountered Tommy Elliot, who joked about Martha Wayne's death. In response, Bruce beat him up. Later down the line, Wayne encountered Elliot once again, albeit in a friendlier environment. The two ended up in somewhat good terms, but their relationship didn't really turn into what it was in the comics.

10 THE BATCAVE'S ORIGIN

The Batcave is one of the DC universe's most fascinating locations. In most incarnations, the cave was an underground tunnel located beneath Wayne Manor that served various purposes (including being an escape route for slaves during the Civil War). The location was eventually discovered by Bruce Wayne, who restructured it as his base of operations. Keeping up with its reinvention of the Batman mythos, Gotham took a different approach with the cave.

This time around, it wasn't an unused section of Wayne Manor. Instead, it was Thomas Wayne's secret office, which he used to uncover the shadiness of his company. Bruce and Alfred eventually found the office, and discovered Thomas' covert efforts. The cave hasn't taken a prominent role in the show, but we'll hopefully see more of it as Bruce continues to embrace his vigilante persona.

9 AZRAEL'S SECRET IDENTITY

6 Theo Galavan As Azrael Gotham

Back in the '90s, DC introduced a character named Jean-Paul Valley, aka Azrael, an antihero who served the ancient Order of Saint Dumas. The character became quite popular, and ever since his debut, fans have been asking to see him in live-action. Comic book faithfuls got excited to know that Gotham would introduce the antihero, but to their surprise, the prequel series put a completely different spin on the character.

In the show, Azrael was a man named Theo Galavan, a descendant of the disgraced Dumas family, which was run out of Gotham years prior, following a conflict with the Waynes.

As an adult, Theo made it his mission to avenge his fallen ancestors. Sadly, the show didn't leave much room to introduce Valley as another Azrael down the line, since it's established that the Order of Saint Dumas was in fact the Galavan family.

8 BARBARA KEAN'S CRIMINAL LIFE

Jim Gordon has had a complicated romantic history in the comics, but so far, his most recognizable partner has been his first wife, Barbara Eileen Kean (mother of Barbara Gordon, aka Batgirl). Their romance was quite a rollercoaster ride on the printed page, so fans were excited to meet Gotham's version of Barbara, and see where her relationship with Gordon could go. Surprisingly, the show turned Barbara (and inherently her relationship with Jim Gordon) upside down.

At one point, the character suffered a mental breakdown. She then murdered her parents and turned to a life of crime, eventually becoming a feared figure around Gotham's underworld. This turn also marked the end of her relationship with Jim. Given how far off the rails Kean has gone at this point, it's unlikely we'll ever get to see her turn back to the light side or continue her romance with Gordon.

7 HUGO STRANGE DIDN'T KILL BRUCE WAYNE'S PARENTS

In most Batman incarnations, Thomas and Martha Wayne's murders were the result of a random mugging gone wrong. This took quite a toll on Bruce, as he couldn't accept the fact that their deaths were an instance of being in the wrong place at the wrong time. That's been a powerful message throughout most of Batman's history, but Gotham shook things up by turning the crime into an intricate conspiracy.

During the show's second season, it's revealed that the Wayne murders were actually orchestrated by Hugo Strange, a gifted psychiatrist and close friend of Thomas Wayne.

Despite their longtime friendship, Hugo decided to indirectly hire a man named Matches Malone to murder Thomas after he uncovered Strange's bizarre experiments, which were being funded by Wayne Enterprises.

6 SCARECROW'S ORIGIN

Scarecrow has a fascinating history in the comics. Having been traumatized as a child by his father, Jonathan Crane decided to study the human mind, and he pursued a career in psychology. Once a doctor, he started experimenting on patients, and slowly turned into the Scarecrow. Similar to others on this list, Gotham set aside the character's comic book backstory in favor of a drastically different origin story.

In season one, Crane was introduced as an insecure young man who helped his father create a fear-erasing formula. Jonathan's father completed the serum, and he injected his son with it. Unfortunately, that left Jonathan in a permanent state of fear, and led him to become the Scarecrow from a very early age. Given how Jonathan has already started a criminal career in the show, fans should probably not expect the character to follow his comic book path any time soon.

5 BRUCE AND SELINA'S FRIENDSHIP

Gotham's Bruce Wayne isn't a people person, but he still has some friends, one of his closest being Selina Kyle. Wayne met Selina shortly after his parents died, and the two quickly became allies. Throughout the show, they've gone on insane adventures together, ranging from taking on mob bosses, to challenging the Court of Owls. Bruce and Selina's friendship has developed into something quite special, and their dynamic remains one of the show's most compelling aspects. As great as it is, however, their relationship isn't faithful to Batman's source material. In the comics, Batman and Catwoman first met as adults.

The specifics of their first encounter vary from writer to writer, but they were never really childhood friends.

Seeing how much Selina and Bruce have gone through in Gotham's four-year run, it will be interesting to see their adult-selves interact with each other years down the line.

4 PENGUIN BEING IN LOVE WITH THE RIDDLER

Penguin and Riddler have always had a rocky relationship in the comics because, more often than not, their power-hungry personalities end up clashing. Gotham threw that animosity away in favor of giving the two evil-doers a strong bond. As the series progressed, Nygma and Cobblepot became friends, and eventually, a twisted romantic tension started to brew between the two.

This development greatly excited fans, but for a while, the possibility of seeing them as a couple seemed slim at best. Fortunately, fans' fantasies became a reality when it was revealed that Oswald was in love with Nygma. Sadly, their romance wasn't meant to be, as Nygma only saw Cobblepot as a friend. Even though their relationship ultimately didn't lead anywhere, it's great to know that DC is willing to explore different sides of its characters.

3 JOE CHILL DIDN'T KILL BATMAN'S PARENTS

Gotham kicks off with Thomas and Martha Wayne being shot to death by an unknown assailant. Following a brief period of mystery, the killer was revealed to be Matches Malone, a hitman hired by Hugo Strange. Viewers were happy to learn the identity of the man who murdered the Waynes, but the reveal probably irked its fair share of Batman faithfuls due to its departure from comic book mythology.

In the comics, a random mugger named Joe Chill is the one responsible for killing the Waynes.

As for Matches Malone, he's an alias Bruce Wayne uses when he needs to infiltrate the criminal underworld. Given how intricate the murder of Martha and Thomas Wayne has become in Gotham, we probably shouldn't expect to see Chill pop up in the show anytime soon.

2 MAKING JEROME A TEMPLATE FOR THE JOKER

Given his unpredictable nature, off-colored jokes and sinister demeanor, fans assumed that Jerome Valeska was Gotham's interpretation of the Clown Prince of Crime. As the years went by and speculation increased, however, we learned that wasn't the case. Instead, Jerome will serve as inspiration for the individual who'll become the true Joker. As exciting as seeing the rise of the Joker in Gotham City may be, this take on the villain is one of Gotham's biggest departures from comic book lore yet.

In DC comics continuity, Joker wasn't modeled after any particular bad guy or figure. Even though he remains a mystery to this day, it's understood that Joker crafted his own persona, and it was his uniquely unpredictable personality that made him such a feared presence around Gotham's criminal underworld. Hopefully, the show will do justice to the legendary baddie once he comes around.

1 BRUCE WAYNE BECOMES BATMAN AS A CHILD

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Ever since it premiered, Gotham has been on a bit of a rush to have Bruce Wayne become Batman. In the span of four years, young Master Wayne has gone from a scared little boy, to a crime-fighting master who prowls the rooftops of Gotham at night, looking for criminals to beat up. It's an interesting take on the character, but as longtime Batman fans will know, that's not how things went down in the comics. On the printed page, Bruce Wayne traveled the world and learned a variety of skills to be able to fight crime.

It took years for him to fully hone his skills, and he didn't become Batman until well into his 20s.

Changing Bruce's heroic journey as drastically as Gotham did could have become an incredibly controversial topic. Surprisingly, though, Wayne's transformation has so far been one of Gotham's most well-received storylines.