Nikola "Nik" Mrdja (born 30 November 1978) is an Australian former soccer player, who played as a striker. Mrdja had a career spanning several National Soccer League (NSL) and A-League clubs from 1998 to 2011, as well as a brief spell in Sweden with AIK in 2004. Mrdja made one appearance for Australia, in a friendly against Argentina in 2007.