High Quality Content by WIKIPEDIA articles! Vipera berus, the common European adder or common European viper, is a venomous viper species that is extremely widespread and can be found throughout most of Western Europe and all the way to Far East Asia. Known by a host of common names including Common adder and Common viper, adders have been the subject of much folklore in Britain and other European countries. They are not regarded as highly dangerous; the snake is not aggressive and usually only bites when alarmed or disturbed. Bites can be very painful, but are seldom fatal. The specific name, berus, is New Latin and was at one time used to refer to a snake, possibly the grass snake, Natrix natrix.