Peter Thiel, left, and Elon Musk, are two members of the so-called "PayPal Mafia. "Associated Press A group of early 2000s PayPal employees and founders came to be known as the "PayPal Mafia." The members have all gone on to impact Silicon Valley by founding and developing major companies. The group includes Elon Musk, Peter Thiel, Reid Hoffman, and the founders of both YouTube and Yelp. What do the founders of YouTube, Yelp, Tesla, and LinkedIn have in common?