Robert Downey Jr. may only play a superhero in Marvel’s “Avengers” films, but he’s become a real-life superhero to a young boy.

In a video released Thursday, the actor presented a working bionic prosthesis to 7-year-old Alex.

He was born with a partially developed right arm.

The actor greeted him as Tony Stark and brought along an Iron Man arm of his own to match Alex’s specially made prosthetic.

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