A female Robber Fly Cerdistus sp (Asilidae).
This is a medium sized species of robber fly, perhaps a couple of centimetres from hypodermic style mouth to the tip of her long sword like ovipositor. I've never been bitten by one, but apparently they are perfectly capable of injecting a person with their venom. This venom will almost instantly paralyse their normal insect prey, but in a person would just cause a painful itchy lump lasting a couple of days.
According to my robber fly expert contact who kindly identified this fly for me there are hundreds of undescribed species in the genus Cerdistus. This one was photographed in Ben Boyd National Park on the New South Wales coast.
Our posts on Sundays have an Australian theme. You can read our other Australian posts here.