David TennantThen and now: David TennantOur favourite TV stars haven't always been so glam.

Long before David Tennant's Doctor was voted the coolest character on TV, he played a cross-dressing barmaid in the 90's comedy series Rab C Nesbitt.

And that's not the only shocker.

The X Factor's Mr Nasty, Simon Cowell, made his TV debut way back in 1990 as a contestant on cheesy game show Sale Of The Century.

And while we're on the subject of X Factor judges, who could forget Dannii Minogue's turn as rebellious teenager Emma Jackson on Home and Away during the early 90's?

Alex Zane introduces clips of some of the early embarrassing moments in many a celebrity's fledgling career.

Child stars such as Britney Spears, Ant and Dec, and Sarah Michelle Gellar have some shameful skeletons in their respective closets, while some stars' first TV appearances are simply cringe-worthy. Anyone remember Emma 'Baby Spice' Bunton's appearance as a mugger in EastEnders? We'd rather forget it too.

These humble, and frequently embarrassing, celebrity beginnings are sure to get celebs curling their perfectly manicured toes and screwing up their botoxed faces in shame. But from our point of view, it's brilliant car crash TV.