Adventurer Archaeologist Jim Cook from Yu-Gi-Oh! GX. He seriously plays the part, having a pet crocodile that he carries around (not a pet to him; to Jim, Shirley is family), and his Duel Disk is shaped like a boomerang.
'Boomerang' however, the supervillain from Marvel Comics, is much more affable if not as dangerous or competent.
Film - Animated
Jake from The Rescuers Down Under, a kangaroo rat and champion outdoorsman with whom Bernard battles for Bianca's affection.
The Easter Bunny, of all characters, is portrayed this way in Rise Of The Guardians. It requires an Australian accent to make the line "I'm a bunny" sound badass. Helps that he's voiced by Hugh Jackman.
Film - Live Action
Mick Dundee, Paul Hogan's character in Crocodile Dundee, is the trope codifier (much to many Australians' dismay). Something of a subversion, since his famous claims turn out to have been substantially exaggerated, and he's a bit clueless when out of his element. Still decidedly tough, though. They also meet an aborigine friend of Dundee who is an urbane city dweller who is just happening to be in the bush for a visit and they can hear him stumbling in the dark about complaining that he hates being there.
The Drover in the film Australia was clearly designed with this stereotype in mind, complete with the use of "Crikey!" As such, he references several other famous Badass Australians.
Mad Max: "Mad" Max Rockatansky. And many of his friends.
The globe-trotting hunter Robert Muldoon is portrayed this way in Jurassic Park, though most of his badassery is informed. He's said to have traveled the world, hunting the most dangerous animals there are, though he's eventually caught and devoured by velociraptors.
He's apparently supposed to be white Kenyan, although his accent definitely sounds more Aussie than Afrikaans.
In Pacific Rim, the Australian Jaeger, Striker Eureka, is the most advanced and most powerful Jaeger, being a Lightning Bruiser armed with thermalSting-Blades, brass knuckles, and chest missiles. And when their Jaeger is disabled, the pilots climb outside and take potshots at a kaiju with flare guns to keep it distracted and away from civilians. Basically, it's surprising they don't challenge kaiju to games of knifey spooney.
Herc: [grabbing the flare guns] Now, we have a choice here: either we sit and wait, or we take these flare guns and do something really stupid.
Striker Eureka's father-son pilots, Hercules and Chuck Hansen, both qualify as well. Unfortunately, their accents vary from "awkward, but you can tell he's trying" (Herc/Max Martini) to "the Sniper would facepalm" (Chuck/Robert Kazinsky). Made worse by the fact that 'Chuck' is not a nickname that is even used in Australia; if anything, Charles would be shortened to 'Chas' instead.
Exaggerated to hilarious extremes with SAXTON HALE, pictured above, the "loose canon" inventor / adventurer / asskicker.
Of course, the entire nation of Australia is like this in the Team Fortress 2 canon, being a nation in which every citizen sports a huge mustache and is a paragon of awesome manliness (even the women). The Sniper is apparently the only Australian without a mustache, although he's be no means a pansy. The discovery of the element Australium is responsible and has made Australia the world's leading country.
Steve Irwin, the Crocodile Hunter, the ballsiest animal rights activist ever to walk the Earth. As his nickname implies, Irwin is mostly known for wrestling crocodiles, which he had done since the age of nine. He based his persona on Crocodile Dundee.
The whole Irwin family counts. Steve's wife, Terri, even became an Australian citizen.
While not damaging to his legacy, Irwin's tragic death was something of a subversion of the trope, as he was killed by a stingray, which isn't even considered that dangerous among sea creatures.
Billy Sing, Australia's greatest sniper in WWI. Born in the state of Queensland, and notably unusual (in terms of this trope) for being ethnically half-Chinese. General William Birdwood, commander of Australian and New Zealand Army Corps (ANZAC), told Lord Kitchener that "if his troops could match the capacity of the Queensland sniper the allied forces would soon be in Constantinople." The enemy forces specifically assigned a champion Turkish sniper to assassinate the man. When said sniper had Sing in his sights, Sing shot first, and was the only one of the two to walk away alive.
Along simlar lines was Caleb Shang, a Chinese-Australian soldier and something of a soldierly jack-of-all-trades, worked as both advanced scout, sniper, machine gunner, stretcher bearer, anything the regiment needed him to be. He was the most highly decorated non-white soldier of the ANZAC forces, including Billy Sing.
Just about every dangerous animal from that continent. Tawny Frogmouths, huge birds with red eyes and wide, reptile-like mouths. Dingos. The Inland Taipan, the most venomous snake in the world. And, of course, saltwater crocodiles.
Huntsman spiders may be giant and hairy, but they're really quite gentle... Or maybe that's just what they want us to think. These are, after all the same spiders as the 'giant crab spiders' and 'rain spiders' of Brazil, Florida, and many other equatorial to temperate regions. Presumably named so due to their tendency to drop out of the sky like giant man-hunting, parachuting crab-spider ninjas.
Ned Kelly, infamous Irish Australian bush-ranger, outlaw and now firmly entrenched figure of folk-lore.
Sir John Monash, World War One general and last man ever knighted on the field of battle. Held responsible by King George for winning the entire damned war. One notable quote: King George commented that they just 'might' win the war using Monash's tactics. Monash's reply, a single incredulous 'might?'
The way he reported it in his diaries, the King began a sentence with the words "If we win this war—" at which point Monash interrupted: "If we win?". It was rumoured at one point that if the war had stretched into 1919, the King intended to sack Field-Marshal Haig and put Monash in charge of the entire British Army.
Hugh Jackman is renowned for playing particularly Badass characters and... pretty much nothing else. This may or may not be because Hugh Jackman is arguably the world's most famous Australian actor.
Somewhat subverted, as when he's not playing a badass, he's playing in a musical or romcom, and was known specifically for these roles prior to breaking out into badass action roles. He's still a badass though.