Nice photos Synapse, but you left out the cool ones . There's too many so I'll go best of each animal family. Most of them you don't see very often, but I've seen all but the Taipan at least once outside a zoo. Blue-ringed octopus is the only one that is common here in Victoria. My younger sister used to poke them with sticks to make them glow blue.
Box Jellyfish (Chironex fleckeri) - Most lethal jellyfish in the world and one of the most dangerous animals in the world.
Blue-Ringed Octopus - One of the most dangerous animals in the world.
Inland Taipan - Most venomous land snake in the world.
Marbled Cone Snail (Cone Shell) - 7th most poisonous animal in the world
Synanceia (Stone Fish) - The most venomous fish in the world and one of the most dangerous animals in the world.
Sydney Funnel-web Spider - One of the most dangerous spiders in the world.
Estuarine Crocodile (saltwater crocodile) - Largest living reptile. 4-6 metres in length.
Paralysis Tick - Releases a toxin slowly into host which causes paralysis