1. Justin Bieber
In 2009 a pre-pubescent Biebs was a blossoming YouTube star, posting vids of his Stevie Wonder, Michael Jackson and Ne-Yo covers. His online success landed him a meeting with Usher and history was made. Remember the swoop haircut?

2. Kate Upton
In 2012, voluptuous actress and model Kate Upton inadvertently became a YouTube sensation when celeb photographer Terry Richardson posted the one-minute Cat Daddy vid that mesmerized men (and women) around the world.

3. Michelle Phan
Beauty guru Michelle Phan got her makeup tutorials in 2007. Now, at 28, her YouTube channel has over 7.5 million followers and she’s well on her way to creating a lifestyle empire. She recently launched Ipsy Open Studios to help other aspiring entrepreneurs follow in her footsteps.