The core appeal of the fantastic and iconic Halo series has always revolved around the Spartans, genetically-engineered super soldiers that can flip over a tank with one hand while holding off the entirety of an alien invasion with the other. Still, imagine the guts and willpower it'd take to be a comparatively normal human being expected to stand up the very same intergalactic terrors that give even the Spartans a run for their money!
There you have the United Nations Space Command, or UNSC. Comprising the practical entirety of human military might in the galaxy, these brave and woefully mortal souls face down everything from Covenant fleets to parasitic Flood outbreaks. Clad in UNSC-issued cardboard as opposed to the MJOLNIR power armor of their Spartan counterparts, their bones are actually breakable. Of course, that doesn't even come close to deterring them from the front lines when duty calls. To illustrate just how hardcore they are, keep scrolling to check out some of the biggest badasses among their ranks.
10 Staff Sergeant Marvin Mobuto
We never get an official nod to this remarkable marine during the events of the actual games, but his story is explored through the book Halo: The Flood, and is way too badass to pass up an honorable mention. Sergeant Mobuto was among the marines that landed on Installation 04 during the events of Halo: Combat Evolved.
Separated from his squad shortly after landing, he's identified as a potential Reclaimer by 343 Guilty Spark and set to the task of recovering the Index from the infamous Library. Alone, Mobuto fought his way deep into the Library before being overcome by the Flood, as a mere man. For context, this task required every ounce of the Master Chief's superhuman Spartan endurance.
9 Dr. Catherine Halsey
Including Cortana on this list felt a bit like cheating, given that she's an AI construct and not technically human, but we're totally including the woman whose brain her programming was based on — she's technically ONI affiliated, of course, but the lady deserves her due. Dr. Halsey is an absolute boss, having spearheaded the success of the SPARTAN-II program, developed indispensable AI constructs like Cortana, and put in the hours perfecting the iconic MJOLNIR power armor.
That said, she is definitely a conflicted character. She's quite a Machiavellian, believing that the ends justify the means. In this context, the ends amount to producing a super soldier capable of protecting the human race with the SPARTAN-II program, and the means are kidnapping children and subjecting them to brutal training regimes.
8 Fleet Admiral Lord Terrence Hood
Lord Hood is an understated character, serving in a mostly administrative role for his part in the actual games. He has a litany of commendations to his name, and a sterling military record. But his no-nonsense attitude and bulldog tenacity during the Battle of Earth played a major role in saving the planet. Besides, any character necessitating Ron Perlman as a voice actor has to be a total badass.
Although he's practically an immovable object when standing against his enemies, Lord Hood is an honor bound warrior through and through, showing a begrudging respect towards the Arbiter for his assistance to the Master Chief, and entering into a pact with him that he refuses to compromise.
7 Sergeant John Forge
Sergeant Forge was a marine serving aboard the UNSC Spirit of Fire during the events of Halo Wars. He was tough, capable, and almost impossible to kill, earning the respect and loyalty of the marines under his command by leading from the front.
He even commanded the respect of the Spartan complement assigned to the Spirit of Fire, which is no mean feat. If that's not enough, he managed to single-handedly best the Covenant Arbiter Ripa 'Moramee in hand-to-hand combat, and walk away with enough grit to sacrifice himself so the Spirit of Fire could escape with its crew.
6 Veronica Dare
Despite being an ONI operative first and foremost, Veronica Dare is more than capable of hopping into a drop-pod and kicking as much ass as the ODST troopers she commandeers and fights alongside during the events of Halo 3: ODST.
Veronica assumed command of the ODST squadron under Gunnery Sergeant Edward Buck, and continuously showed her tactical prowess and combat know-how as she led the team in securing a renegade Engineer.
5 Captain James Cutter
Captain James Cutter commands the UNSC Spirit of Fire during the events of Halo Wars and Halo Wars 2. Although his tactical savvy is an obvious consideration, his bravery and willingness to put everything on the line to protect humanity from the ravages of the Covenant and the Banished really set him apart.
His character really shines during the opening events of Halo Wars 2. After his ship comes out of hyperspace in unknown territory and they find themselves beset by the forces of the Banished, he's encouraged to retreat by the recovered AI construct Isabel, which he abjectly refuses to do, opting to deploy his forces to hold the line while they attempt to re-establish contact with the UNSC.
4 Gunnery Sgt. Edward Buck (Pre-Spartan)
Yes, yes, Sergeant Buck eventually becomes a Spartan, as seen in Halo 5: Guardians. Buck was a badass long before he underwent the transformation into a UNSC super soldier, though.
His aloof and comical demeanor may be misleading, but make no mistake, Sergeant Buck is a hardened veteran. You pretty much have to be when you opt into the legendary ODST, let alone find yourself assigned to command a squad of them. He'd definitely earned his stripes by then, having served in almost every major conflict in the war against the Covenant.
3 Captain Jacob Keyes
Ah, Captain Keyes. The man's reputation as a tactical genius is hard-earned and well deserved. Our first meeting with him on the bridge of the Pillar of Autumn is a memory no Halo fan is likely to ever forget, though he really needs to keep his pistol loaded.
His history is a lengthy and convoluted one, full of military accolades and covert involvement in the SPARTAN-II program alongside Dr. Halsey. We get a real taste of what makes him a true badass during the events of Halo: Combat Evolved, where he's kicking ass and taking names alongside the troops under his command. Unfortunately, he falls prey to the Flood infestation, but manages to hold on to the last vestiges of his humanity to the bitter end.
2 Commander Miranda Keyes
Much like her father, Commander Miranda Keyes isn't too comfortable barking orders from the comfort of an office chair. She's got her mother's brains to boot, essentially a weapon of their own when we're talking Dr. Halsey. When it comes time to get her hands dirty, she's more than willing to put her life on the line and plunge headlong into the action.
The list of heroics to her credit is pretty lengthy, but her shining moment directly preceded her untimely demise during the events of Halo 3. With the Chief and Arbiter too far away to stop the Prophet of Regret from using Johnson to activate the Ring, she crash-lands her Pelican into their position, hopping out and immediately gunning down Brutes on her lonesome with a shotgun before beign overwhelmed by numbers.
1 Sergeant Avery Johnson
Sergeant Johnson is the definitive monument to UNSC badassery, and is probably the most infinitely-quotable character throughout the first three titles in the Halo franchise. He knows what the ladies like, he knows what the aliens like, and whether he's faced with Covenant forces, the Flood, or, in his words, "God's own anti-son-of-a-b***h machinegun," you can safely bet a mountain of cash that he's coming out swinging.
It was with a heavy heart that we had to say goodbye to him towards the end of Halo 3, as the enraged 343 Guilty Spark mortally wounded him upon learning that he and the Chief planned on destroying the Ring. Still, he definitely went out with a bang.