Lady Gaga achieved a major milestone over the weekend, passing the 10 million follower count on Twitter. Gaga is the first to reach the 10 million mark on the social networking site.

Mashable reported that the pop star was also the first person to reach 10 million fans on Facebook. Gaga now has more than 34 million fans on Facebook.

Gaga's achievement sent us out in search of the most popular tweeters, and you may be surprised by who ranks high in the list.

The top 10 celebrities with Twitter thumbs are: Lady Gaga: 10 million, Justin Bieber: 9.7 million, Barack Obama: 8 million, Britney Spears: 7.8 million, Kim Kardashian: 7.5 million, Katy Perry: 7.3 million, Ashton Kutcher: 6.7 million, Ellen DeGeneres: 6.6 million, Taylor Swift: 6.4 million and Shakira: 6 million.