Nah, they're small as... but nasty little feckers.
You only need to worry about funnel webs in NSW, these can kill. Redbacks in Victoria have a potent bite but rarely, almost never kill. Snakes, though... be careful. If you have your wits about you though, you'll spot snakes and just leave them alone.
In general, the more northerly you are, the nastier the spiders, snakes and jellyfish.
Oh, I forgot. Jeez, how could I? You'd never know. We don't have grizzlies but we have drop bears. Be warned. They don't give a shit. They're just nasty. No. 1 reason for carrying a bowie in the bush. Ask anyone!