David Marcus (born April 12, 1973) is a French, Swiss, and American entrepreneur and executive. He is the former president of PayPal  and is the Vice President of Blockchain Products at Facebook. 
Marcus started his career at 23 when he founded his first venture, GTN Telecom, and served as the Chairman and CEO until GTN was acquired by World Access in 2000. 
Zong was acquired by eBay's PayPal in 2011 for $240 million, and Marcus joined PayPal as Vice President and General Manager of Mobile division of PayPal. 
Under his leadership, PayPal launched its offline mobile card reader solution, PayPal Here . In April 2012 he was picked to take over the leadership of the company as the President, when then President Scott Thompson left PayPal to join Yahoo . 
In 2014, Marcus left PayPal to lead Facebook's mobile messaging initiatives. 
David helped bring Messenger from under 300 million users to over 1 billion users worldwide.