Billy Parish (born September 11, 1981) is an American environmental entrepreneur, author, and activist. He is the co-founder and CEO of Mosaic Inc., a leading financing platform for U.S. residential solar and sustainable home improvements. Mosaic recently received a $220 million equity investment from private-equity firm Warburg Pincus and was named one of the 10 most innovative companies in energy by Fast Company in 2013 and 2014.