Agkistrodon is a genus of venomous pit vipers found in North America from the United States south to northern Costa Rica. Six species are currently recognized, all of them polytypic and closely related. Common names include: cottonmouths, copperheads, and cantils. Some varieties are known as "moccasins" or "moccasin snakes", such as Agkistrodon piscivorus, the water moccasin.