Hollywood's Old Flames: Can You Believe They Once Dated?

Sandra Bullock and Ryan Gosling

Back in 2001, Ryan Gosling and Sandra Bullock werean item.The beautiful pair dated for two years, and Gosling, 31, calls Bullock, 47, one of his best gal pals ever, grouping her with Rachel McAdams (whom he dated for four years).Ryan said, "I had two of the greatest girlfriends of all time. I haven't met anybody who could top them."

Michelle Trachtenberg and Pete Wentz

Fall Out Boy and Ashlee Simpson's ex Pete Wentz once romanced "Gossip Girl" actress Michelle Trachtenberg in 2006.Pete revealed that Michelle dumped him because he was living a "frat boy" lifestyle after first moving to L.A.Wentz is currently dating model Meagan Cooper.

Scarlett Johansson and Josh Hartnett

After meeting on the set of "The Black Dahlia" in 2006, Scarlett Johansson and Josh Hartnett became an item and dated for a year.Their split was caused by conflicting schedules -- similar to why Johansson later divorced her husband, Ryan Reynolds.

Alyssa Milano and Justin Theroux

He may be known as the man who stole Jennifer Aniston's heart, but actor Justin Theroux once had a thing for Alyssa Milano.Milano and Theroux turned their on-screen romance in 1997's "Below Utopia" into the real deal.Theroux later dated stylist Heidi Bivens for 14 years before dumping her for Aniston.

Kelly Preston and Charlie Sheen

Kelly Preston may be happily married to John Travolta, but did you know she was once engaged to Charlie Sheen?Another shocker... in 1990 it was reported that Sheen accidentally shot Preston in the arm!More than 20 years later, Sheen explained in his 2011 "Torpedo of Truth" tour, "When she lifted my pants off the scale in the bathroom, the tiny revolver I used to carry fell out of the back jeans pocket and hit the floor and shot a bullet right between her legs. So she got hit with shrapnel from the toilet bowl."The marriage was called off.

Famke Jansen and Ben Affleck

Although they denied ever being a couple, Ben Affleck and "X-Men" star Famke Jansen were spotted kissing at a NYC bar in 2001.Their romance quickly fizzed, as Jansen reportedly dumped Affleck for not being interesting enough.

Winona Ryder and Matt Damon

Before smart phones, Facebook and Twitter, Winona Ryder and Matt Damon shared a romance in the late '90s.They quickly became Hollywood's "it" couple, after first meeting at a New Year's Eve party in 1997, when his pal Ben Affleck was hanging out with his GF at the time, Gwyneth Paltrow.After dating for three years, the couple called it quits in 2000.

Amanda Seyfried and Alexander Skarsgard

Amanda Seyfried recently admitted to hooking up with "True Blood" hottie Alexander Skarsgard... while she was still with ex Dominic Cooper!Seyfried explained, "We dated. He's superfunny, but I was too inolved with Dom."

Sienna Miller and Sean Combs

Following their first encounter at the Golden Globes in 2007, P. Diddy and Sienna Miller were spotted partying together.While that doesn't mean they were necessarily an item, Diddy was reportedly seen sneaking into Miller's hotel room after a night of clubbing.Both reps denied the two ever dated.

Kristen Bell and Matthew Morrison

Way before Matthew Morrison became known as the lovable teacher on "Glee," the actor and Kristen Bell were involved while they were both undergrads at NYU.Bell, who is engaged to Dax Shepard, said, "We actually dated very briefly."