The Joker has seen many different faces throughout the years of cinema. Giving the character a little different personality from person to person.
My first introduction to the mad clown was from Jack Nicholson in (1989) BATMAN. Where he plays a man looking to change Gotham to his own image, while being on top of the pedestal.
"This town needs an enema!" - Joker
Then years later we had Heath Ledgers version in (2008) THE DARK KNIGHT. Where he plays it more as a chaotic mad man looking to disrupt all that is normal in Gotham.
"Some men just want to watch the world burn." - Alfred
Then in (2016) came out SUICIDE SQUID, the Joker played by Jared Leto. Playing it more like a hoodlum jyst looking for the next thrill.
"I can't wait to show you my toys." - Joker
Now in (2019) came Joker, preformed by Joaquin Phoenix. Which shows a man looking for acceptance in the world and to belong. With a passion to become a comedian, he finally snaps from the cruel reality he lives in.
"Is it just me, or is it getting crazier out there?" - Arthur Fleck
What will we see in the future, who knows? These are my takes on the characters alone.