There are several genera of funnel web spiders, but the most common ones in Australia are Atrax, Hadronyche, and Illawarra. They vary in size and color, usually black or brown, with shiny carapaces. The males are generally smaller and less robust than the females.

Scientists from Australia and Germany have classified a new, highly venomous species of spider, Atrax christenseni, known as Big Boy. It is very large and highly venomous, with bites that can be fatal.