The blockbuster comicbook film "Joker" has a terrifying ending, but there was an even more shocking and horrifying alternative ending to Todd Phillips movie, starring Joaquin Phoenix in the starring role.

In a Fatman Beyond podcast recently, filmmaker Kevin Smith claimed that there was one alternative ending planned for the now blockbuster movie, reports independent.co.uk.

In the climax of the official version, Arthur Fleck aka Joker (Phoenix) follows Thomas and Martha Wayne and kills them, leaving young Bruce Wayne (who then goes to become Batman). In the alternate ending, Joker kills Bruce as well.

"Originally, the ending in the hospital was different. He's in the hospital and he laughs, chuckles, and he says, ‘I was just thinkin' of something funny'. What was supposed to happen was you flashed back to the death of Thomas and Martha Wayne, and it was him (Joker) killing Thomas and Martha Wayne and the boy was screaming and crying and he turned to walk away and he turned back, shrugged, and shot the kid. Credits," he said.

Smith said he was told the ending by someone "who works in the business" and called it "reliable information". He said: "It was too f***ing good not to share and I f***ing hope it's true".

The Warner Bros. project has become the highest-grossing R-rated movie of all time, and has crossed the $ 1 billion mark at the worldwide box office. In fact, the impact is deep as it has sparked conversation around mental health. A follow-up to film is also in the works.

Phoenix is being considered as a contender of Best Actor Oscar this year.