• Bradley Cooper arrives for the premiere of "American Snipers", towards the end of 2014. Admittedly, not the best hairstyle, but the 40-year-old hottie still manages to work it.Reuters
  • Bradley Cooper at the Metropolitan Museum of Art Costume Institute Gala Benefit in 2014.Reuters
  • Bradley Cooper at the premiere of "The Hangover Part III" in 2013.Reuters
  • Not many men can pull off a mustache, but here Bradley Cooper is, rocking a pimp-style mustache and still managing to look cool.Reuters
  • Cooper gets candid with cast member Mike Tyson at the premiere of "The Hangover Part II" in 2011Reuters
  • Bradley Cooper at the premiere of "Valentine's Day" in 2010.Reuters
  • ESActor Bradley Cooper sports curly long hair at the ShoWest Award in 2009.Reuters
  • Keeping up with the trends of 2007, Bradley Cooper is seen sporting spiked up hair with blonde highlights at the season five premiere screening of the FX series "Nip/Tuck".Reuters
  • Bradley Cooper with then-wife Jennifer Esposito in 2006Reuters
  • Bradley Cooper poses for pictures on the red carpet during the premiere of "Wedding Crashers" in 2005.Reuters

Bradley Cooper, the voice of beloved Rocket Raccoon in "Guardians of the Galaxy" and People's Sexiest Man Alive of 2011, celebrates his birthday on Monday, 5 January. While his boyish charm and laid-back personality make fans wonder "how old is Bradley Cooper really?", he is actually turning 40. 

He must be the brand ambassador for the phrase, "40 is the new 30", because he does not look a day older than when he played the testosterone-fueled, preppy, and violent Sack Lodge in "Wedding Crashers", almost a decade ago. 

The two-time Academy Award nominee has had many looks over the years, some that made him look rugged, other that made him seem like the new-age metrosexual man; all of them hot. He may either celebrate the big 4-0 with a huge Hollywood bash with A-lister friends or spend it on a calm, cuddly date with his girlfriend Suki Waterhouse. 

His fans can celebrate the "American Sniper" actor's birthday with a slideshow of some of his hottest looks in the red carpet over the years. For those of you raunchier fans, try to find solace in the following pictures tweeted by like-minded fans who worship his body, as much as his talent.

And, he has proven time and again that one can be just as sexy with clothes on.