Sony, Microsoft, The Wall Street Journal, The New York Times, Time Magazine, The New Yorker, Mashable, TechCrunch, Coca Cola, Mercedes Benz, Samsung, Star Wars, PlayStation, General Motors, NFL, Bloomberg, MTV, Facebook, eBay, Google, LinkedIn, Flickr, NASA, and TED. Jay Z, Beyoncé, Katy Perry, Justin Timberlake, Kobe Bryant, The Rolling Stones, Malala Yousafzai, Sylvester Stallone, just to name a few.
There have been over 143 version-updates of WordPress resulting in major and minor (security, maintenance etc.) releases. Volunteers all over the world contribute to the WordPress project: WP updates regularly and continually. This results in functionality and security. WordPress 4.4 alone had 471 contributors.