5 - Funnel Web Spider
Almost everyone is scared of spiders (even the 'tough guys' who try to convince people they find them 'cute') and one of the least pleasant in the Land Dahn Unda, not to mention most famous, is this fellow. There are several species, all of which are venomous and have large fangs capable of biting through a fingernail or shoe. They do at least do you the courtesy of adopting a 'warning posture' before striking, which is handy... assuming you even see them. Fortunately there are anti-venoms available; otherwise this scary scurrier would be higher on the list!
4 - Stonefish
Long regarded as the most venomous fish in the world, the stonefish is particularly dangerous owing to its habit of hanging around in shallow water (or even out of the water altogether where they can survive for a good while) and, as its name implies, looking like nothing more threatening than a mere stone. If you step on one, though, you're in trouble due to the needle-like spines along its dorsal fin which are tipped with potent neurotoxins. Stings are excruciatingly painful and, if not treated with an anti-venom quickly, can lead to paralysis, loss of limbs, and even death.
3 - Brown Snake
There are many dangerous snakes in Australia and representing them here is this fellow. There are several subspecies but all look and act similarly, though only the larger examples tend to cause problems for us overgrown chimps, fortunately. Several of those are among the top ten most venomous snakes in the world and all can easily kill an adult human, and they're easily started too, needing little provocation to strike. Best advice? Steer clear of all scraggly undergrowth!
2 - Box Jellyfish
Jellyfish are strange creatures. They don't even have brains and yet they've been wibbling around the world's oceans for millions of years, more or less unchanged. Pretty much all of them are venomous to one degree or another and most are best avoided, few more so than the box jellyfish. There are several species but the most dangerous kind live in the coastal waters around... you guessed it, northern Australia! They're pretty small but their clusters of long tentacles can deliver an extremely powerful venom that results in excruciating pain, and can potentially cause death as soon as two minutes later. Oh dear :(
1 - Blue-Ringed Octopus
Surprised to see a seemingly-unassuming octopus at the top of a 'dangerous animals' list? So was I, but this scary creature is now one I fear a great deal. Or I would if I lived in Australia, at least, for all four different species can be found in various coastal areas of this vast country, with some only found there! They're small for octopuses, ranging from 5 to 8 inches, but their venom is powerful - 1,200 times more toxic than cyanide and therefore easily potent enough to kill humans - and each of them apparently carries enough of it to kill 26 adults within a few minutes. The good news is that their bites are not painful. The bad news? There's currently no anti-venom. Which basically means you probably won't know you've been stung until you're paralysed, unable to breathe, and creeping towards death. One of the deadliest creatures in the world then - great, thanks evolution!