Followers: 4 million
Sample tweet: "2 killed in attack at #Germany airport are #USAirForce airmen, reports indicate"
The oughts weren't great for CNN, a decade that saw the original cable news network lose market share to rival networks' shoutfests. That the onetime media trendsetter has struggled to keep up was further demonstrated by the rollout of its breaking-news Twitter handle — which had actually been created and nurtured by Brooklyn-based Web developer James Cox. CNN formally placed the handle under its umbrella in April, 2009. Just four months later, @CNNbrk was the go-to source for outside coverage of the 2009 Iranian uprising. With that early history behind it, the handle now has more followers than any other media brand (not counting Oprah), and regularly tweets on news items ranging from Lindsay Lohan's rejection of a plea deal to the search to calculate the number of orphans in Japan following the March 11 earthquake.
(Disclosure: CNN is owned by the same parent company as TIME magazine.)