Iron Man

Tony Stark — genius, arms manufacturer, heir to Stark Industries — is ambushed in Afghanistan by terrorists armed with his own weapons. Shrapnel lodges near his heart. A fellow captive, Ho Yinsen, builds an electromagnet to keep it out; Stark builds a miniaturised arc reactor, then a suit of armour, and escapes. Yinsen dies covering him.

Stark shuts down weapons manufacturing. His business partner and father's old colleague Obadiah Stane — who arranged the ambush — tries to kill him for it. Stark wins.

Then he does the thing that starts everything: at a press conference, instead of reading the cover story, he says "I am Iron Man." No secret identity. The modern superhero era begins with a public admission.

Post-credits: Nick Fury appears in Stark's living room. "You've become part of a bigger universe. You just don't know it yet."