Hymenoptera: Formicidae
Myrmecia forficata
Composite photo of a Myrmecia forficata species Bull Ant wandering around and threatening the photographer.
The Bull Ant's jaws look unpleasant but being grabbed by them would be no big deal if the Bull Ant didn't, while it was doggedly hanging on, then forcefully apply the sting from its opposite end. Now that is unpleasant!
And such a friendly looking little creature too.