Stars who've made big bucks away from showbiz

The millions that Simon Cowell makes from shows like X Factor, American Idol and his 'Got Talent' series obviously aren't enough, as the music mogul has just released a line of top-of-the range headphones, branded X Headphones, in a joint venture with Sony.

Cowell said his headphones would be the best on the market, saying they were "like being in the recording studio when the records are made. The sound is that clear". They're likely to be a massive hit as the canny TV judge plans to use the headphones on X Factor, promoting them to a worldwide audience of millions.

He's not the only star who makes big bucks away from showbiz. Click through the gallery to see how the likes of Angelababy, Siti Nurhaliza and Jay Chou make those extra bucks from away from their day jobs.