Michael O'Brien (born June 27, 1950) is an American photographer noted for his portraiture and documentary photography.Over the past four decades, O'Brien has photographed subjects from presidents, celebrities, and financiers to small-town Texans, including ranchers, beauty queens, writers, and bar owners.O'Brien has completed three books: The Face of Texas: Portraits of Texans (2003), updated with 24 new photographs in 2014; Hard Ground whose portraits of homeless individuals are paired with poems by Tom Waits (2011); and The Great Minds of Investing (2015), a collection of 33 portraits of famous investors such as Warren Buffett, Charlie Munger, Joel Greenblatt, and Bill Ackman, with accompanying profiles written by William Green.