"My mother always tells me to smile and put on a happy face", Phoenix, as Arthur Fleck, says in a voiceover. "I thought my goal was to bring laughter and joy to the world".
The trailer continues with a montage of scenes highlighting the character's mental health issues, his transformation into the villain and the rampage he would soon go on.
I'm intrigued enough by Joaquin Phoenix to hope this works out and he can do something special with this character, which does reside high on the curve thanks to Heath Ledger. Are you excited to see the upcoming Warner Bros. film?
Joaquin Phoenix perfectly captures the essence of one of the comic book world's most iconic baddies, as viewers are treated to the background of the clown killer, with his heartbreaking treatment through life culminating in the transformation.
What stands out from the trailer compared to past versions of the Joker is that we are finally going to get a real origin story or at least one we can believe.
"I ended up landing more in the realm of a psychopath-someone with very little to no conscience towards his acts".
The trailer for Joker gives us a look at how Arthur Fleck - the man who will eventually become the Joker - transitions from happy-go-lucky clown to cynical monster.
For Haddish, "people only think that 'Oh, she's just a mother, she's just this, she's just that, ' but now we can make you laugh".
Since then Jared Leto has tried and failed to replicate some of that magic with his own twist on the character in the lamentable Suicide Squad film.
Find out exactly how Joker got those scars - or at least how he cracked in the '80s and went full-psychopath - when Joker hits United Kingdom cinemas on 4 October.