Julian Knowle (born 29 April 1974) is an Austrian male professional tennis player. Being a born left-hander, Knowle is now one of the few on the ATP Tour who plays his forehand, backhand, and even volleys double-handed. He was Austria's most successful doubles player in history by reaching world no. 6 in the ATP doubles rankings in January 2008, before being matched by Jürgen Melzer, who reached no. 6 in September 2010, and overtaken by Alexander Peya, who reached no. 3 in August 2013.