Robert Downey Jr. turns 51 this year, and we're celebrating by looking back at his transformation from the guy on Sarah Jessica Parker 's arm to one of the most successful action heroes in movie history. The actor has had his ups and downs over the years, but thanks to his raw talent, determination, and hard work, he's managed to become the Hollywood success story that everyone compares our current troubled stars to. Keep scrolling to see all the best RDJ shots, from the '80s to today!
Robert and SJP looked like an '80s It couple when they attended the premiere of Slam Dance in LA.
Robert held on tight to a nearly unrecognizable SJP at a gala in LA.
Robert and Sarah Jessica looked very in love at the Oscars.
Robert and SJP looked like a sweet young couple in Santa Monica.
RDJ was by Sarah Jessica's side when he attended the premiere of her film L.A. Story in London.
Robert cleaned up nicely for the MTV Movie Awards.
Robert had really long hair when he took a snap with Sheryl Crow  at the Billboard Music Awards.
RDJ was too cool to pose at the MTV Movie Awards.
Robert showed off his frosted tips at the MTV Movie Awards.
Robert looked like a cool character at an LA party.
Robert sported his trademark sunglasses to the Emmys.
Robert took his son to the premiere of Austin Powers in Goldmember.
Robert wore a floppy hat to the Toronto International Film Festival.
Robert looked happy to release his first record in LA.
Robert looked like he was ready to join a boy band when he attended the Cannes Film Festival.
Robert showed a bit of gray while attending the Oscars.
A mustachioed Robert put his arm around his wife at the premiere of Tropic Thunder in LA.
Robert sported a unique suit to his hand and footprint ceremony at Grauman's Chinese Theatre in Hollywood.
RDJ sported longer locks at the LA premiere of Due Date.
Robert had his wife by his side at the premiere of The Hangover Part II.
Robert looked healthy and happy at a press conference for The Avengers in LA.
Robert wore retro glasses to the premiere of Iron Man 3 in Hollywood.
While speaking onstage at the Hollywood Film Awards, Robert looked pretty damn dashing in his eggplant-hued suit.
RDJ was sitting pretty at the 41st Annual People's Choice Awards in LA.
It's a testament to Robert's youth that he was able to go toe-to-toe with Chris Evans at the Kids' Choice Awards in March.