Darren Christopher O'Day (born October 22, 1982, in Jacksonville, Florida) is a Major League Baseball relief pitcher for the Texas Rangers. He played college baseball for the University of Florida. O'Day is one of few Major League pitchers to throw submarine pitches.
He made his major league debut with the Los Angeles Angels of Anaheim in 2008 and was selected by the New York Mets in the Rule 5 Draft on December 11, 2008.
He made the Mets' roster out of spring training and was a regular member of the bullpen rotation in the first month of the 2009 season. He was widely quoted in the media on the death of his former teammate Nick Adenhart. He was designated for assignment by the Mets to make room for Nelson Figueroa. The Texas Rangers claimed him on April 22, 2009 and he made his debut the same day in extra innings against the Toronto Blue Jays, just minutes after getting to the bullpen from the airport. His arrival was so quick that he had to wear the jersey of Kason Gabbard in his first appearance.