George Nicholas Kontos (born June 12, 1985) is an American professional baseball player. A relief pitcher, he plays for the San Francisco Giants of Major League Baseball (MLB). Kontos made his MLB debut for the New York Yankees in 2011 before he was traded to the Giants before the 2012 season. Prior to playing professionally, he played college baseball at Northwestern University. He bats and throws right-handed.

Kontos attended Niles West High School in Skokie, Illinois, where he was named the high school baseball player of the year in Illinois in 2003. He also lettered in golf and basketball.

Kontos attended Northwestern University as an economics major, where he played for the Northwestern Wildcats baseball team in the Big Ten Conference. Despite his never winning five games in a season, or finishing a season with an earned run average (ERA) below 5.00, the New York Yankees selected Kontos in the fifth round of the 2006 Major League Baseball draft after his junior year.

Kontos signed with the Yankees after his college career and played for the Staten Island Yankees of the Class A-Short Season New York–Penn League in 2006, winning the league championship. With a 7–3 win–loss record, 2.64 ERA, and 82 strikeouts in 78 innings pitched, Baseball America named Kontos a Short-Season All-Star. He pitched for the Tampa Yankees of the Class A-Advanced Florida State League in 2007 and the Trenton Thunder of the Class AA Eastern League in 2008. After starting the 2009 season with Trenton, he was promoted to the Scranton/Wilkes-Barre Yankees of the Class AAA International League.