Australia's News9 reports that Domenic, who has cystic fibrosis, was appointed an honorary Avenger by Robert Downey Jr. after saving his city in a mission organized by Make-A-Wish.
Domenic was joined by his sidekick and brother Joseph, who played the Marvel character "War Machine."
The pair rescued a woman, Ms. Joy, from the clutches of a villain, then had a final showdown with his archnemesis at the Sydney Opera House. He defeated the villain surrounded by a crowd of cheering onlookers.
After his victory, New South Wales Police Commissioner Andrew Scipione presented Domenic with the Commissioner's Award for Gallantry. He had given Domenic his mission earlier in the day by video message.
"Iron Boy, we need your help," Mr. Scipione told Domenic via video message, in the "top secret" operations room. "If I could make one wish it would be for you to help us Iron Boy."
Downey Jr. tweeted, "Go get 'em, Domenic!" to the boy, adding that he "sent a very special boy on a top secret mission today".
Australian actor Chris Hemsworth, who plays Thor in his own film franchise and the Avengers franchise, also chimed in on Twitter with a simple, "Go Dom!"
According to Make-A-Wish, when Domenic was asked what super power he would possess above all else, he answered "to heal."