Platypus has a stinger in its tail so be careful of that one chances of seeing one extremely remote though
Koalas are drunken little mongrel thing that has claws that will rip you to pieces and they have a transmittable sti, on top of that the little bastards bite... don't be fooled do not pick them up the wild ones are not like the domesticated version u see people playing with in the zoo.
after that there is a frilled neck lizard that will run at you climb up your pant leg and bite you on the Yarbles or pecker
Then there is the other introduced species of Hogs they will go you and are a real problem,
And then still there are packs of feral dogs gettin about in some parts
Meanwhile driving down the streets of most towns you will see foxes because you aren't allowed to shoot at them in town, clever creature, this one wont hurt you.
except that one time a relative had one cornered up a tree with a shotgun and it decided to jump from the top and broke both front legs and was still trying to get away...
Then we have fresh water crocodiles they seem to leave you alone (don't trust them)
but wait there's more there are Salt water crocodiles and they will actively see u as a meal ticket (at night time if your in the northern part of Australia get a spotlight and point it out into the swamp you will have thousands of little reflective eyes lookin right at ya
and to think haven't even started on spiders, snakes, Insects or the other innumerable aquatic life (blue ringed octopus, Man o war jellyfish etc,)
Me personally will still walk around in a pair of thongs holding a tinny