VIDEO : Today is Robert Downey Jr.'s 51th Birthday

Today is Robert Downey, Jr.?s birthday. One of the biggest, highest-grossing actors in Hollywood, Robert Downey Jr. is known worldwide for his transformative role as Iron Man/Tony Stark. Since 2008, Downey Jr. has portrayed the Marvel Comics character in Iron Man, Iron Man 2, Iron Man 3, The Avengers, and Avengers: Age of Ultron (along with a cameo in The Incredible Hulk).