Gréta Arn (born April 13, 1979) is a Hungarian-born German former professional tennis player. She competed on the WTA Tour from 1997 to 2016.
Arn achieved a career-high singles ranking of world No. 40 in May 2011 and a career-high doubles ranking of world No. 146 in April 2007. She won two WTA singles titles: in Auckland in 2011 and in Oeiras in 2007.
Representing Hungary, Arn competed in the Fed Cup from 1997 to 2011. She also represented Germany in the Fed Cup in 2012.