No doubt he was a decent fellow. There are approximately 40,000 other people who died on exactly the same day he did, none of whom were in a movie as the Joker. They were probably decent people too.
Tom Petty [Final Fantasy XV] (9%)
Bondage Finch [Bondage Finch Adventures] (12%)
Melisandre, the Red Woman [Game of Thrones] (43%)