The Common European adder, also known as the black adder or the northern viper is a venomous snake that is extremely widespread and can be found throughout most of Western Europe and as far as East Asia. The color pattern of entirely brown ones with faint or clear, darker brown marketing, and on to melanistic individuals that are entirely dark and lack any apparent dorsal pattern.
However, most have some kind of zigzag dorsal pattern down the entire length of their bodies and tails.

Common European adder