The sika deer (Cervus nippon) also known as the spotted deer or the Japanese deer, is a species of deer native to much of East Asia, and introduced to various other parts of the world. Previously found from northern Vietnam in the south to the Russian Far East in the north, it is now uncommon in these areas, excluding Japan, where the species is overabundant. Its name comes from , the Japanese word for "deer"; in Japan the species is known as the .