Justin De Fratus, American baseball player
Justin Andrew De Fratus (born October 21, 1987), is an American former professional baseball relief pitcher. He played in Major League Baseball (MLB) for the Philadelphia Phillies, from (2011–2015).

De Fratus grew up in Oxnard, California and played baseball in high school prior to playing at Ventura College. The Philadelphia Phillies selected him in the 11th round of the 2007 Major League Baseball draft. De Fratus methodically moved his way up through the Phillies farm system, spending about one year at each level, from rookie to Class A, and then moving through two levels per season in 2010 and 2011. In 2011, De Fratus made his MLB debut and, by 2013, he was a regular member of the Phillies bullpen after a few years of splitting time between the big leagues and Triple-A. In 2014, De Fratus used his slider to "dominate the league", and establish himself as a reliable reliever, capable of pitching in late-inning situations.

De Fratus has a two-pitch repertoire that consists of a fastball and a slider, the latter of which is his out pitch. He embraces a propensity to work quickly on the mound, and use a lower arm slot. Off the field, De Fratus is a member of the Roman Catholic church, and uses baseball to strengthen his faith. He sees evangelism as a duty of Christians, and would like to go to seminary when he finishes his baseball career.