1 Crazier Than The Joker: Thanos.
Harleen Quinzel and her adorably psychotic alter-ego are far more frightening than the Joker ever thought about being.
Deathstroke is simply a far more formidable threat than the Joker.
Darkseid being, the God of Evil, and the incarnation of Fascism.
Harley Quinn is crazier as Joker is able to see that settling down with her is just not possible even though he would like too. Joker is self aware enough to understand that being king of criminal underworld and his lifestyle does not make for a stable domestic life.
The Joker does not reciprocate her love and is in fact incapable of romantic emotion as he sees people only as tools to further his own plans. Harley is in denial of this fact and prefers to view him as an antihero until she eventually has to come face-to-face with his complete disregard for her.
In the story, the Joker takes Harleen Quinzel to the chemical plant where he originated and pushes her into a vat of chemicals against her will, which bleaches her skin and drives her insane, resulting in her transformation to Harley Quinn, similar to the Joker's transformation in his origins.
"I'm an American, I [CENSORED] hate Nazis," Joker says in a panel from Injustice: Year Zero #4 teased by writer Tom Taylor. "I'm a homicidal maniac, not a traitorous bigot."
Despises: Red Hood
In all of Gotham and further away, there's probably no-one else who hates the Joker as much as the Red Hood does.
In contrast to most of the entries, one of the darkest versions of Joker ever created is when Martha Wayne becomes the supervillain. This tragic turn for her comes during the Flashpoint storyline where Bruce was killed on that fateful night instead of her and Thomas.
Emperor Joker was a form The Joker took after tricking Mister Mxyzptlk into donating 99.99% of his reality powers to him. As a direct result, he became near-omnipotent and created a hellish world in his own image.
Joker IQ is estimated to be around 160 IQ, which is not really surprising. Meanwhile Batman's IQ is around 192. The Joker is, in fact, more twisted than intelligent. Joker has chosen to use his intelligence in a different way than his archenemy Batman, who uses it to strengthen his arsenal and improve Gotham.
It seems that for all of his bluster, the Joker may have been secretly intimidated by and jealous of Harley Quinn. The Clown Prince of Crime revealed his true feelings the moment he saw his sidekick show genuine potential as a solo villain.
Adrien Brody
He was apparently in line to play the Joker in 2008's The Dark Knight, before the role eventually went to Heath Ledger.
A female version of the Joker appeared as part of DC's Tangent Comics line in her own one-shots (Tangent Comics: The Joker #1 in 1997 and Tangent Comics: The Joker's Wild! #1 in 1998). This Joker bore little resemblance to the traditional interpretation of the character and instead was modeled on Duela Dent.
5 The Joker Often Doesn't Seem To Care About Anything Other Than Batman. Over the years, Joker has proven he truly cares about two things: Batman, and the people connected to Batman.
Bane has a great deal of respect for Batman; this isn't a secret, the two have fought many times and even become allies at one point. Bane would even take up the mantle of Batman at a later date, when Bruce is once again not around.
Joker may be one of the smartest and most cunning villains in DC history, but even he knows not to try and outsmart the Riddler. While the Joker is a criminal genius rivaled by almost no other villain in fiction, even he knows the Riddler is his intellectual better.
While fans got to hear many memorable quotes from Joker in Batman: Arkham, the series also revealed what his greatest fear is supposed to be. As it turned out, The Joker feared being forgotten more than anything else because it meant nobody was afraid of him anymore, rendering all his crimes void.
Most human villains are definitely afraid of the Joker. This is because the Joker can be threat to anyone on Earth, day to day switching targets. The joker isn't powerful, but he is unpredictable. This is what makes many people fear him.
While Jack Nicholson famously landed the role of The Joker, Burton approached another respected actor to play the villain: John Lithgow, who talked the young director out of casting him. In the process, Lithgow was responsible for one of the greatest regrets of his own career.
In the film, Harleen Quinzel voluntary jumps into a vat of acid that turns her into Harley Quinn on her own accord simply because her love and obsession for the Joker trounced her own vision of self-worth simply because the Joker asked her if she “would die for him.”
In the latest issue of Flashpoint Beyond #5, the Joker's real name has been revealed: Jack Oswald White. This is something that fans of DC and the character have greatly appreciated, and that is that the identity of the Joker is something that many have always tried to find out.
Harley Quinn started gave the Joker the nickname of Mr. J when she was still a pyschiatrist at Arkham Asylum. She also often calls him Puddin.