Ask Chris #314: Does Batman Carry The Mark of Zorro?
Q: How essential is The Mark of Zorro to Batman's origin story? -- @TheKize A: Strictly speaking, I don't think it's necessary. For one thing, while I'm actually not sure where it was introduced, the idea that young Bruce Wayne was watching The Mark of Zorro on the night his parents were murdered was at least canonized in stone in the opening pages of The Dark Knight Returns, which means that there were almost 50 years where Batman got along just fine without that element. On top of that, there have been plenty of Batman stories that go in a different direction, and it doesn't really hurt the mythology behind the character to make it something else. But that said, The Mark of Zorro being the last thing Bruce Wayne sees before his world ends and he makes the choice to become Batman certainly makes it a whole lot better.