Having a much younger or much older significant other has become somewhat of a Hollywood tradition. From older actors reliving their youth with much younger ladies to cougars on the prowl for a boytoy, it seems age really is just a number for many stars.

The latest May-December romance that caught many people by surprise is between Mary-Kate Olsen, 25, and Frenchman Olivier Sarkozy, 42, (brother to former French president Nicolas Sarkozy).

"MK is constantly complaining about boys not being mature enough for her," a source told Us Weekly, confirming rumors that the pair is dating. "She got the kids out of her system. Now being a businesswoman dominates her time, and she is rarely impressed with guys."

Though their 17-year age difference is, well, quite large, the Olsen and Sarkozy's romance isn't the most shocking. Hollywood legend Dick Van Dyke, 86, married a woman 46 years his junior in 2012, while Hugh Hefner's girlfriend (and former fiancee) Crystal Harris is 60 years younger than him.

Check out some other celebrity romances with some major age differences below:

Loading Slideshow...
  • Adrienne Maloof & Sean Stewart

    Age difference: 19 years

  • Demi Moore & Vito Schnabel

    Age difference: 24 years

  • Sharon Stone & Martin Mica

    Age difference: 27 years

  • Amber Tamblyn & David Cross

    Age difference: 19 years

  • Eddie Murphy & Paige Butcher

    Age difference: 18 years

  • Mary-Kate Olsen & Olivier Sarkozy

    Age difference: 17 years

  • Jennifer Lopez & Casper Smart

    Age difference: 18 years

  • Hugh Hefner & Crystal Harris

    Age difference: 60 years

  • Rod Stewart & Penny Lancaster

    Age difference: 26 Years

  • Jeff Goldblum & Emilie Livingston

    Age difference: 30 years

  • Courtney Stodden & Doug Hutchison

    Age difference: 35 years

  • AnnaLynne McCord & Dominic Purcell

    Age difference: 18 years

  • Calista Flockhart & Harrison Ford

    Age difference: 22 years

  • Annette Bening & Warren Beatty

    Age difference: 21 years

  • Tom Cruise & Katie Holmes

    Age difference: 16 years

  • Michael Douglas & Catherine Zeta-Jones

    Age difference: 25 Years

  • Alec Baldwin & Hilaria Thomas

    Age difference: 26 years

  • George Clooney & Stacy Keibler

    Age difference: 18 years

  • Clint Eastwood & Dina Ruiz

    Age difference: 35 years

  • Kelsey Grammer & Kayte Walsh

    Age difference: 25 years

  • Bruce Willis & Emma Heming

    Age difference: 24 years

  • Celine Dion & René Angélil

    Age difference: 26 years

  • Donald Trump & Melania Trump

    Age difference: 23 years

  • Jaston Statham & Rosie Huntington-Whitely

    Age difference: 19 years

  • Dick Van Dyke & Arlene Silver

    Age difference: 46 years

  • Marc Anthony & Shannon De Lima

    Age difference: 18 years

Related on HuffPost: