5 Surprising Facts About the Common European Adder You Never Knew 1. It’s Europe’s Only Widespread Venomous Snake The Common European Adder is the most widespread venomous snake in Europe, found from the UK and Scandinavia all the way to Russia and parts of Asia. Despite being venomous, its bite is rarely fatal to humans. 2. Highly Variable in Color Adders can be grey, brown, reddish, or even black (melanistic). They’re easily recognized by their zigzag pattern down the back, though in melanisti