Notorious ladies' men, including Michael Bublé and Harry Styles

You can't blame a young man on the cusp of worldwide fame for enjoying his new heartthrob status, but when notorious ladies' men start turning to you for dating advice, perhaps that's a cue to have a few quiet nights in watching TV in your pyjamas!

That's just what's happened to Harry Styles from One Direction. Canadian crooner Michael Bublé is among the most desired musicians on the planet, but he admitted that he regrets missing his chance to ask Harry for some tips when they met. "I have one regret - and that's I wish I'd asked Harry Styles for women advice, just like: 'How do you get things done, Harry?'"

Sure, Michael is happily married, but his endorsement of the 18-year-old boyband singer has propelled the young star into an elite club - A-list womanisers. Check out some of Hollywood's notorious ladies' men - from Jude Law and George Clooney to the grand-daddy Casanovas Hugh Hefner and Jack Nicholson.