Proko, aka Stan Prokopenko, is now an online institutional resource for all things on learning to draw the fundamentals of anatomy. He studied and taught at Watts Atelier, a notable artist workshop located in Southern California established by the venerable Jeff Watts. It is here where he established himself as a portrait and caricature artist. Over the years, he produced a number of videos which can be found on YouTube, notably it is his very accessible videos on the Loomis method which helped kick off the Proko craze. You can also access additional videos at his site, http://www.proko.com, both free and for a premium.
Stan has a lot of personality, and it really shines in the videos he and his team post online. Stan has also done a number of interviews you can find online. More recently, Chris Oatley of the Oatley Academy interviewed Stan on his ArtCast episode 107 on the virtue of distractions can help you become a more focused artist.
On top of all the books, online library of tutorials, and generally sage advice that Proko dishes out in great volumes he has also created an iOS app Skelly, that provides you, the artist, with instantly poseable human figures. The app works as a compliment to Proko’s own tutorials on how to build the human anatomy without reference, freeing the artist to create believable, fluid poses of humans from any angle.