Protesters in Chile, Beirut and Hong Kong adopt clown masks
Protesters of the world: think twice before putting on that Joker mask
Joker, Todd Phillips' blockbuster, was controversial before it even hit the screens.
The FBI reported an increase in online threats linked to the release. Many of the posts referred to a 2012 mass shooting that occurred at a showing of The Dark Knight Rises in Aurora, Colorado.
Joker focuses largely on how its title character, as his origin story reaches its climax, inspires a wave of riots, protests, and general mayhem in Gotham City, a classic battleground pitting the poor and oppressed against the rich.
She says that themes from the film - such as "the representation of the failures of neoliberal capitalism, and its disastrous consequences" - have resonated with protest movements around the world.
Mattias Frey, professor of film and media at the University of Kent, told Wired that the protesters have used the mask for the symbolic value, while divorcing "all the evil stuff, the crazy stuff".
He said: "On some level, we identify with the Joker, in the sense that he's someone who has a purpose. In this film, he's given a reason - he's bullied.
"I think if you asked the audience ‘do you sympathise with blowing up the world?’ they would probably say no, but some of the radical energy – this rage against the establishment – obviously does appeal to them."
Frey added: "He's a symbol of the oppressed, the downtrodden, the ignored, the abused.
"But the mask also carries a warning – basically, ignore me at your peril. I will strike back."
Forbes predicts that Joker will probably top $1 billion at the worldwide box office. The comic book movie - with a budget of $60 million - has already made around $934 million in cinemas around the world.
They also note that it is the first - and possibly last - 2019 release not related to Disney or Marvel that could make over $300 million at the US box office this year.
The critics consensus reads: "Joker gives its infamous central character a chillingly plausible origin story that serves as a brilliant showcase for its star - and a dark evolution for comics-inspired cinema."
Why Joker masks are the perfect political protest symbol
Towards the end of Joker, the title character stands atop a car, revelling in the midst of a crowd of protesters made up in his image. Now, almost inevitably, the character has become a symbol for real-life protestors too.
At its release, the film - which stars Joaquin Phoenix in a dark take on the Batman villain - prompted moral panic and a warning issued by the US Military. It was feared that it would inspire lone killers - particularly incels - but so far, Joker has proved more inspiring to mass protest movements across the world.