19 ex celebrity couples you had no idea once dated

Think you're well-versed in celebrity gossip, and all that goes on between the rich and famous? Think again, because you've probably forgotten all about some of the flings and romances of the past.

But it's true, there have been a number of surprising (and sorely missed) couplings between the stars of Hollywood. So let's take a trip down memory lane and revisit some former flames.

1. Bradley Cooper and Renée Zellweger

After meeting on the set of Case 39, they dated for two whole years before splitting in 2011.

2. Angelina Jolie and Jonny Lee Miller

Jolie's first marriage (and divorce) was to Miller between 1996 and 1999, but is often overshadowed by her marriage to Billy Bob Thornton, and her most recent split from husband number three, Brad Pitt.

3. Justin Timberlake and Jenna Dewan-Tatum

Yup, before she married (and split from) Channing Tatum, Dewan-Tatum was one of Timberlake's backup dancers, and they got together after his breakup from Britney Spears.

4. January Jones and Ashton Kutcher

The Mad Men star dated Kutcher for three years, before calling it quits in 2001.

5. Jared Leto and Cameron Diaz

Diaz and Leto (yep, I know!) dated for four whole years from 1999, and were even engaged before parting ways.

6. Scarlett Johansson and Jack Antonoff

Antonoff dated Johansson for two years – even taking her to prom – before he settled with Girls actress Lena Dunham (whom he later split from too).

7. Reese Witherspoon and Jake Gyllenhaal

The Legally Blonde star met Gyllenhaal on the set of Rendition in 2007, and were together until 2009.

8. Lenny Kravitz and Nicole Kidman

The pair were engaged until Kidman declared she "wasn't ready" in 2003. But hey! Things are fine now and Kidman even worked alongside Kravitz's daughter, Zoë, in Big Little Lies.

9. Sarah Jessica Parker and Robert Downey Jr.

Things were looking serious for the pair, until they split in 1991 after seven years together, citing Downey's drug addiction as the cause.

10. Sandra Bullock and Matthew McConaughey

The pair had a secret-but-not-so-secret relationship after working on A Time to Kill together in the late 90's.

11. Ryan Gosling and Sandra Bullock

Gosling fell for the actress (who is 16 years his senior) after meeting on the set of Murder by Numbers in 2002. They dated for a year before cutting ties.

12. Sheryl Crow and Owen Wilson

Wilson and the singer dated from 1999 until 2001.

13. Matt Damon and Winona Ryder

The pair ended things in 2000 after a two-year romance following rumours of cheating from both sides.

14. Jake Gyllenhaal and Kirsten Dunst

The actors dated for two years before splitting in 2004.

15. Tom Cruise and Penelope Cruz

Cruise and Cruz met on the set of Vanilla Sky in 2000, and dated for three years.

16. Mila Kunis and Macaulay Culkin

Yep, Kunis and the Home Alone star dated for eight years, before they broke up in 2011.

17. Leonardo DiCaprio and Gisele Bundchen

The serial model-wooer had one of his most serious relationship with the Victoria's Secret model. They were on-and-off for six years, before she married Tom Brady.

18. Rachel McAdams and Michael Sheen

The actors met while filming Woody Allen's Midnight in Paris. They confirmed their romance on the red carpet at the Cannes Film Festival back in 2011, before breaking up in 2013.

19. Alanis Morrissette and Ryan Reynolds

Morrissette and Reynolds met at Drew Barrymore's birthday party in 2002, and announced their engagement just two years later. It lasted three years, before they announced to the public that it was over.

It seems like everybody dated everybody! While you'd think it'd be kind of awkward given that you're bound to run into at least one of your exes at any Hollywood event, it seems like everyone's quite chill about it.