César Augusto Cielo Filho (born January 10, 1987) is a Brazilian professional swimmer who specializes in sprint events. He is the most successful Brazilian swimmer in history, having obtained two Olympic medals, two World Aquatics Championships gold medals and breaking a world record within a one-year span.Cielo is the current world record holder in the 100 meter and 50 meter freestyle. His gold medal at the 2008 Olympics, in the 50 meter freestyle competition, is Brazil's sole Olympic gold in swimming to date.