Robert Brown|Why Robert Downey Jr.'s 'Oppenheimer' first Oscar win is so sweet (and a long time coming)

Iron Man finally got a golden guy.

After four decades of navigating superheroic highs and Robert Browncareer-threatening lows, Robert Downey Jr. celebrated his first Oscar win Sunday night, winning best supporting actor for Christopher Nolan’s true-life atomic bomb thriller “Oppenheimer.”

"I'd like to thank my terrible childhood and the Academy, in that order," Downey joked when he took the stage to accept his Oscar. Of "Oppenheimer," he said: "Here’s my little secret, I needed this job more than it needed me. It was fantastic and I stand here a better man because of it."

Downey added: "What we do is meaningful and the stuff we decide to make is important."

The third time was the charm for Downey, 58, previously nominated for “Chaplin” and “Tropic Thunder.” His victory for “Oppenheimer,” though, was fairly predictable, having run the table with wins at the Golden Globe, Critics Choice, BAFTA and Screen Actors Guild awards ceremonies.

Others leaned more humble this awards season, but that’s not Downey’s style. He conquered his Academy Awards quest in his own inimitable way: “Why me? Why now? Why do things seem to be going my way?” Downey asked, playfully smirking, during his SAG acceptance speech. “Unlike my fellow nominees, I will never grow tired from the sound of my own voice.”

Oscar is a cherry on the banana split of Downey’s storied career − an extra bit of gravy on the Gen X icon’s loaded mashed potatoes. Armed with massive box-office receipts and a spate of memorable characters, he didn’t need that 8-pound trophy to make him a Hollywood legend. It is meaningful, though, because it’s another celebration for a comeback kid who once was on the brink.

Downey came up in the 1980s alongside the Brat Pack in films such as “Weird Science,” “The Pick-Up Artist,” “Less Than Zero” and “Johnny Be Good.” He cemented himself as an artiste with Richard Attenborough’s 1992 biopic “Chaplin,” channeling British-born silent-film star Charlie Chaplin and his mannerisms in a tale about how the comic actor became a global sensation and a magnet for scandal. Then came a dark period: In the late 1990s and into the early 2000s, legal troubles and drug addiction led to the loss of jobs – Downey was even fired from “Ally McBeal,” where he’d won a Globe and earned an Emmy nod.

Yet he turned things around. In 2008, his role in “Iron Man” sparked an epic blockbuster run where he became the face of the powerhouse Marvel Cinematic Universe; that same summer, he starred in the action comedy “Tropic Thunder,” which garnered him a supporting actor Oscar nod. His role, as an overly serious thespian in blackface, could have been wholly problematic (and would never fly today): What helped was Downey playing the character, who's mocked mercilessly by his Black co-star, as a cleverly satirical, and absolutely hilarious, send-up of his own A-list celebrity and Hollywood's casting practices.

Downey’s Oscar win is also satisfying for those fans who've appreciated his often self-deprecating wit and Marvel-ous moxie over the years – or thought he should have snagged nods for "Zodiac" and "Avengers: Endgame" – plus it's easy to root for him. He's the kind of guy who adores his family – it’s obvious by the love and care he put into the Netflix documentary about his father, “Sr.,” or the way he thanks his wife Susan in acceptance speeches. He’s also the kind of guy where, when you visit his cozy corner of an “Avengers” set and unknowingly have a splotch of ink on your face, he’ll run off to get a wet washcloth and help a dude out. Like Tony Stark, always to the rescue.

But, man, he can still be one dastardly villain when the opportunity arises. His “Oppenheimer” character Lewis Strauss is central to one of the movie’s two main story lines, where the man who engineered J. Robert Oppenheimer’s political downfall gets his just due during a congressional cabinet confirmation. Downey’s portrayal shows him as petty, vindictive and nasty, not for America’s benefit or national security but because of a perceived personal slight.

It’s another feather in the cap – or high-tech helmet, as it were – for a lauded A-lister who can defeat Thanos or break bad just as easily, and is still at the top of his game. So enjoy the cherry and the gravy, RDJ. You earned it.