Joaquin Phoenix avoided questions over whether his new film may inspire certain viewers to copy the Joker’s actions.
The families of those killed in a 2012 mass shooting at a cinema in the US have expressed concern about the upcoming Joker movie.
Twelve people died and 70 were injured in the attack during a screening of The Dark Knight Rises in Aurora, Colorado.
The killer was dressed in full body armour and armed with guns, including an assault rifle.
Joker, which chronicles the beginnings of Batman’s nemesis, will not air in the cinema where the shooting took place.
The families of those killed in the attack are concerned about the realistic violence in the movie.
They are calling on Warner Bros, the studio behind the film, to make a donation to charities supporting the victims of gun violence.
In a letter to Warner Bros chief executive Ann Sarnoff, the Survivors Empowered group wrote: «We are calling on you to be a part of the growing chorus of corporate leaders who understand that they have a social responsibility to keep us all safe.»
Survivors Empowered was set up by Sandy Phillips and her husband Lonnie, who worked a gun control advocacy group.
Their letter does not ask the studio to stop the release of the film — instead, it asks Warner Bros to «end political contributions to candidates who take money from the National Rifle Association and vote against gun reform».
It also asks the film studio to use their «political clout and leverage in Congress to actively lobby for gun reform».
Mrs Phillips’ 24-year-old daughter Jessica Ghawi was one of those killed in the cinema shooting.
She told The Hollywood Reporter: «I don’t need to see a picture of [the killer]; I just need to see a Joker promo and I see a picture of the killer.
«My worry is that one person who may be out there — and who knows if it is just one — who is on the edge, who is wanting to be a mass shooter, may be encouraged by this movie. And that terrifies me.
«For me, it’s the gratuitous violence that this film glorifies and elevates with the Joker character.»
The Aurora gunman was convicted on 24 counts of first-degree murder and is now serving a life sentence in prison. In the aftermath of the shooting, he was compared to the character of the Joker because of his brightly dyed hair.
Not everybody, however, agrees that the film will cause fresh violence.
Tom Sullivan’s 27-year-old son Alex was killed in the shooting. Mr Sullivan is now a Democratic state representative, who introduced 2020 US presidential candidate and gun control campaigner Beto O’Rourke at a town hall event.
Mr Sullivan does not believe the film will «jumpstart» shootings, adding: «I don’t think that seeing something is the catalyst to, ‘okay, that is what I am going to start to do’.»
However, he did say he would support Warner Bros adding «a blurb at the end or beginning of the movie about directing people to organisations for mental health».
Warner Bros have been contacted for comment.