When it comes to the Joker, it's evident that his moral code is non-existent. He's out for himself and no one else, as he commits crime after crime and slips through the hands of the GCPD. In fact, it makes you wonder why Gotham City has a police department if it's that useless.

Naturally, Batman and the other heroes can't trust a single word that comes out of the Clown Prince of Crime's mouth. They aren't alone, though, as he's just as shady when it comes to his fellow rogues. Not only is he the king of laughs, but he's also become the great betrayer in the DC Universe to just about everyone he meets.

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10 HARLEY QUINN

Put aside all the unhealthy relationship goal fantasies about the Joker and Harley Quinn, because this is one dysfunctional couple. They're constantly on and off that the only way you know they're together or not is via their Facebook relationship status updates.

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Unsurprisingly, the Ace of Knaves has betrayed the Clown Princess more times than anyone can count. From letting her take the fall for his crimes to abandoning her when the cops arrive at the scene of the crime, he has left her high and dry more times than anyone else. It's no surprise that she has trust issues after hanging out with him for so long.

9 THE BATMAN WHO LAUGHS

The Batman Who Laughs is a version of the Batman from Earth-22, who is the perfect hybrid of Bruce Wayne and the Joker. With him unleashed on Prime-Earth and ready to end that world's Batman, you'd think that he'd team up with the Dark Knight's greatest nemesis to finish off the job.

As it turns out, the Clown Prince isn't a big fan of competition. He turned on the Batman Who Laughs when the Dark Multiverse Caped Crusader thought the Joker would use the opportunity to take down two Batmen with one stone. It goes to show that Mr. J has a soft spot for his Batman after all.

8 LEX LUTHOR

Considering the Joker and Lex Luthor are two of the biggest supervillains in the DC Universe, it's remarkable how they can't seem to get along. No matter how many times Luthor extends his hand to the Ace of Knaves, he's always betrayed at the end of the day.

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In Justice League #13, Luthor and Joker double-crossed each other. Initially, Luthor requested that Mr. J join the Legion of Doom. He did under the condition that Luthor not involve the Batman Who Laughs. When Luthor betrayed him, Joker quit the Legion and told Luthor he planned on betraying him from the start. Inception, right?

7 THE RIDDLER

The Riddler and Joker have been at odds with each other since the day they first crossed paths. While they occasionally join forces to cause havoc in Gotham City, their egos inevitably get in the way and they end up going for each other's throats in the process.

In "The War of Jokes and Riddles," these two rogues turned Gotham City into a warzone as they feuded. When all is said and done, though, they always seem to make amends and put aside their history to team up for another crime caper. It's the old adage of "keep your friends close and your enemies closer."

6 SCARECROW

On paper, both of these villains should make a formidable team. Think about it: Scarecrow and the Joker love to play mind games and are more intelligent than the run-of-the-mill criminals in Gotham City. Unfortunately, they just can't seem to get along and trust each other for a long stretch of time.

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At one point in their history, the Joker and Jonathan Crane teamed up to ransom off Gotham City's mayor. After their plan was stopped by Batman, Scarecrow turned on the Joker and sprayed him with fear gas. It had no effect whatsoever on the Clown Prince of Crime, who returned the betrayal by smashing Crane with a chair, repeatedly.

5 HUSH

The Joker's relationship with Hush is complicated as it's linked to the bandaged character's debut in Batman: Hush. The Clown Prince ended up becoming a part of Hush's initial plot to drive Batman to insanity -- something that rubbed Mr. J up the wrong way, inevitably, as he wants to be the one pulling the strings.

The Joker left town for a while, only to return and take his revenge on Hush by installing a pacemaker to control heart. Since then, the two haven't exactly remained pen pals or best of friends. Perhaps there will be an opportunity for them to mend fences soon.

4 HOLIDAY

 

You'd think that the Joker would welcome another maniac into the rogues' gallery, but he's about as jealous as the Real Housewives of Gotham City. Rather than form an allegiance with Holiday, Mr. J thought it a better idea to smoke the city than share its citizens with the mysterious villain.

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In Batman: The Long Halloween, Batman had to put a stop to the Joker as he plotted to release venomous gas over Gotham Square. The reason for the Clown Prince's actions were simple: He believed he'd finish off Holiday that way while the rest of the people would've served as collateral damage.

3 CATWOMAN

In all fairness, this is a tricky entry since Catwoman places both sides. There are times when she's a hero and villain (as well as an antihero), so the betrayals are most likely reciprocal. Still, the Joker and her are hardly ever on the same side at the end of things, no matter where they started.

Undoubtedly, their topsy-turvy relationship stems from Selina Kyle's closeness to Batman. As everyone knows, the Joker sees the Dark Knight as his own BFF and despises anyone who gets too close to him. Think of him as the comic book version of Chip from The Cable Guy.

2 MR. FREEZE

In recent years, Mr. Freeze has been portrayed as a man of principles. He hasn't turned to a life of crime because he wants to get rich or has some lust for chaos; everything is for his wife, Nora. This puts him directly at odds with the Joker, who is a loose cannon and loves anarchy for the sake of it.

In original continuity, the Joker casually put an end to Freeze, a fellow rogue, because he could. Much like Days of Our Lives, however, no one stays buried in comic books and Freeze returned after his character received an origin makeover in Batman: The Animated Series.

1 CARL GRISSOM

Carl Grissom, portrayed by the late Jack Palance, was the mob boss in Tim Burton's Batman. Based on Rupert Thorne, he was the bigshot whom Jack Napier, aka the Joker, reported to before his transformation into the grinning maniac with an affinity for purple and green.

After discovering that Napier was having an affair with his mistress, Alicia Hunt, he set up the events to get his second-in-command offed at Axis Chemicals. Ultimately, the Joker got his revenge by putting bullets in his old boss, but this wouldn't have been an issue if Napier hadn't betrayed Grissom's trust by having an affair with his gal. What a slimeball!

NEXT: Tim Burton's Batman Is Still the Dark Knight's Cinematic Benchmark

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