Joseph Gordon-Levitt is one of Hollywood's hottest guys, but he wasn't always this way. Back in the '90s, when he started his career as an alien on 3rd Rock From the Sun, no one would have guessed that he would later transform into one of the most swoon-worthy celebs ever. Through the years, JGL has donned many looks for roles and in real life, including a bulked-up New Jersey sex addict  and a goofy-faced lip-syncer , and we're rounding them all up below. We'll just forget that he has a girlfriend  for now . . .
Source: Getty 
3rd Rock From the Sun Wasn't His Best Look, but He Was Still Young in the '90s!
Back in 2001, He and Zooey Deschanel Looked Completely Different
At the Treasure Planet Premiere in 2002, This Outfit Happened
In 2003, This Almost-Bowl-Cut Look Was Not a Favorite
The "Long Hair, Don't Care" Mentality Returned in 2004
And He Brought Along Hot-Pink, Patterned Outfits in 2005
In 2006, He Shaved Off All His Hair
Then, Without Warning, in 2007, He Was Completely Clean Cut
But It Was Followed by This Sexy, Scruffy Face For the Film Uncertainty
Then in 2008, He Was Smoldering in Every Way
He Brought Clean-Shaven Smirks in 2008, Too
When (500) Days of Summer Happened in 2009, We Had 500 Reasons to Love Joseph
Then This Bow Tie Wowed Us in 2010
He Looked So Nice, He Wore Them Twice (Actually, All the Time)
Through the Years, His Goofy Faces Have Always Been Hot
And When He Sang in 2010, We Nearly Died
He Even Looks Great in Uniform, as Seen in The Dark Knight Rises
When He Got New Frames in 2012, He Made Glasses Sexy
OK, Just Look at This Smirk. Who Can Deny That?
In 2013, He Displayed His Goofy Charm Yet Again
His Lip-Sync Battle on Late Night With Jimmy Fallon Was a Win
Slow-Motion Running, Anyone?
In 2013's Don Jon, His Bulked-Up Sex Addict Character Even Did It For Us
Source: Relativity Media 
When He Got Goofy With Don Jon Costar Tony Danza in 2013, Our Hearts Stopped
And to Bring It Full Circle, Here He Is With 3rd Rock Costar John Lithgow, 13 Years Later