SAN FRANCISCO (Reuters) - Facebook filed its IPO on Wednesday, setting the stage for the Internet industry's biggest coming-out party and one of Wall Street's most hotly anticipated events of 2012. Here is a look at some of the personalities behind the world's largest social network. 1. Mark Zuckerberg, chief executive and co-founder Zuckerberg, portrayed as a brilliant, ambitious and ruthless empire-builder in the 2010 movie "The Social Network," founded Facebook with Chris Hughes, Dustin Moskovitz and Eduardo Saverin while at Harvard University in 2004. ...