Occupation: Professional tennis player
Previous TIME 100 Appearances: 0
Despite reaching the No. 1 ranking and winning a U.S. Open title in 2005, Clijsters, just 23, retired from tennis in 2007, intent on starting a family. She gave birth to a daughter in February 2008, returned to tennis last year and proved her mettle as a working mom. Clijsters strung together a magical run that carried her to the U.S. Open championship.