Deadly spiders in Europe: How worried should we actually be?

If someone asked you to name a place with poisonous fauna, what would spring to mind? Perhaps Australia, with infamous snakes like the inland taipan (Oxyuranus microlepidotus), or maybe Brazil, home to dreaded creatures like the yellow scorpion (Tityus serrulatus). Europe, however, would probably be low on the list, as the continent is not known for its menacing fauna.