PewDiePie, who is the undisputed King of YouTube with over 32 million subscribers, had his first hit with this video called "Fun With Minecraft Multiplayer."
Bethany Mota, who has built an empire off of her beauty and style videos, was attracting thousands of viewers from the very beginning of her YouTube journey in early 2010. But it was this video addressing bullying and her experiences with bullying that drew in tons of viewers who related to her.
Michelle Phan, with 7 million subscribers, hit the jackpot when she uploaded a "how-to" video about putting on makeup while on an airplane. It even attracted the attention of Lancome, who hired her to be their digital spokesperson after the video went viral.
Tyler Oakley warmed the hearts of his viewers when he came out on YouTube in 2008. The video has over 300,000 views and Oakley currently has over 5 million subscribers on his channel.
Jenna Marbles tricked people into thinking they were good-looking with her massive hit. The video has 59 million views and Marbles has over 14 million subscribers.
Nine years ago, the duo the internet knows as "Smosh" created this Power Rangers theme video. Now, the pair (and some other big names in the YouTube world) are making a movie with Lionsgate.
Sam Tsui and Kurt Schneider (who now both operate under different channels) brought in 34 million viewers when they uploaded this mash up of Michael Jackson songs in 2009.
Grace Helbig has blown up in the last year, after creating YouTube show, "It's Grace." Helbig is currently starring in the film "Camp Takota," which she also co-produced.
Connor Franta, who just created a coming-out video for YouTube, has been uploading since 2011. This video, "How you talk to your parents vs. your friends," brought in lots of fans.
Pentatonix received national attention when they appeared on "The Sing Off" but they were already big on the internet after their acapella version of Gotye's "Somebody That I Used To Know" went viral.
Liam Kyle Sullivan had one of the first major viral videos when he uploaded "Shoes." He then went to television where had a few parts on shows like "Gilmore Girls" and "Alias."
Bo Burnham now tours the country as a comedian and singer/songwriter. "The Twitter Song" was his first big YouTube hit with over a million views.
And, as a bonus! We wouldn't call him a YouTube star...but Justin Bieber did get discovered by Usher after posting covers of songs to the video platform.