Keep in mind that, while this post isn't focused on the movie, the following will contain spoilers for Centurion.
Played by Dominic West in the film, today's GURPS Centurion character is Virilus. General Titus Flavius Virilus, if you want to get tria nomina about it. General Virilus is the general of the Ninth Legion, which is sent into Caledonia (Scotland) to try to wipe out the Picts who defy Roman rule. Virilus is portrayed as the 'head soldier' type: he doesn't view himself as separate from the mass of fighting men under his command. He parties alongside his men, getting into barfights with the rest of them, and exchanging crass jokes with them at all hours of the night while camped. But he's also famed as a successful general and tactician, not allowing over-familiarity with his men to preclude ordering them into famous, bloody victories. Accordingly, he's much beloved by his men, who consider him the consummate brother-in-arms.
This write-up, like Etain previously, is mostly written based on the core GURPS Basic Set. The character gear is from GURPS Low-Tech, and this character features a few skill techniques, which are detailed in GURPS Martial Arts. His gear is a bit more of an expression of what you typically see in GURPS: he has a 'settled' lifestyle, so he gets to spend 20% of his starting wealth on adventuring gear. In this case, that's $3,000, of which he spends $2,400 on a fine Spatha--or thrusting broadsword. The remaining gear (and his horse, as appropriate) is issued to him by Rome, and considered part of the 80% that he doesn't actively spend during character creation.
Virilus [205 pts total]
Attributes [60 pts sub-total]: ST +3 ; DX +1 ; IQ +0 ; HT +1 ; HP +0 ; Will +2 ; Per +0 ; FP +0 
We're introduced to Virilus with an arm-wrestling bar scene, so +3 Strength is pretty much a given. He's capably coordinated, but bullish in his movements, so I deem that's +1 Dexterity. Even though he's a general, he'd get standard Intelligence of 10, as he never seems to work on anything but a basic rational level. A healthy professional soldier with no evidence of strict endurance, he ought to have at least +1 Health. He's a strong-willed, forceful character with +2 Willpower, but the rest of his stats--Hit Points, Perception, Fatigue Points--fall into their standard values as well.
Influence and Wealth [84 pts sub-total]: Languages: Latin (native); Cultures: Roman; Very Wealthy ($15,000 starting, $13,500/month) ; Military Rank 7 , Status 3 (+2 courtesy status due to rank) , Reputation 2 (Romans: famed general of the Ninth Legion, recognized: 7 or less) 
For lower class characters, the influence and wealth categories are an afterthought most of the time. For upper class characters, though, it is going to be a big part of the character sheet. That's certainly the case for Virilus. First, his language and culture is limited to his native familiarity with Rome. As a legion's general, he is Military Rank 7. I gave him Very Wealthy, which is moderately rich by GURPS standards--twenty times average wealth. In GURPS Fantasy, they state that this correlates to Status 5, but that requires a huge Cost of Living--GURPS' way of representing that living the Status 5 high life requires spending more money on food, clothes, and other luxuries. So instead I went with Status 3 with 2 levels of courtesy status that are more a result of his military rank. Finally, I gave him a Reputation. In GURPS a Reputation can be a bonus or penalty to relevant social rolls. The Reputation has a description of its nature and those who are affected by the rep, and a recognition number that shows how easy to spot they are in public. For Virilus, he has a significant Reputation as the hero of Hispania, but he apparently isn't very recognizable, as the emissary in the first act identified him as a common soldier.
Advantages [25 pts sub-total]: Combat Reflexes , Fearlessness 5 
Virilus felt very straight-forward when it came to Advantages. When you see Virilus dive into the bar fight's brawl at the end of his first scene, he mounts a table and kicks a guy in the face without hesitation--that's got to be Combat Reflexes if ever anyone had them. He also seems to be nearly unflappable in the face of his own demise, with a grim sneer as he beckons for death, so he gets a hefty Fearlessness 5. This means that he gets to add 5 to his Willpower when making fear checks, which means he'll hardly ever balk in the face of danger.
Disadvantages[-55 pts sub-total]: Bad Temper (SC: 12 or less) [-10], Chauvinistic [-1], Code of Honor (soldier's) [-10], Duty (extremely hazardous, always on duty) [-20], Gregarious [-1], Lecherous (SC: 15 or less) [-8], Overconfidence (SC: 12 or less) [-5]
As Virilus was simple and easy to assign advantages, he also carries his disadvantages on his sleeve. His introduction involves him converting a heated arm wrestling game into a game of stab-arm and then into a full-on bar brawl, so I think he fits the bill for Bad Temper with a fairly average self control number of 12 or less. In a deleted scene he characterizes Pict society as being childish and primitive relative to Roman society, so he gets Chauvinistic, which is a minor sort of intolerance for anything not your own society. Even given his temper and chauvinism, though, he is a professional soldier with a clear sense of ethics, which gives him a soldier's Code of Honor. Given the mass of bloody battles he references in talking to his men, he gets Duty with the Extremely Hazardous and Always on Duty modifiers. He laughs and pals around with his men to a degree that it is brought up as a detriment to his status, so Virilus easily qualifies for Gregarious, too. When Virilus first meets Etain, who I established doesn't have a super high appearance modifier, his mind and mouth go straight for the gutter, so I gave him Lecherousness with a generous self control number of 15. And finally, his whole legion is ambushed and obliterated so easily I can only assume he suffers from Overconfidence, albeit with an average self control number.
Skills [61 pts sub-total]: Animal Handling (Horses) IQ , Armoury (melee) IQ-1 , Brawling DX+2 , Broadsword DX+1 , -Targeted Attack (Broadsword Thrust/Vitals) Skill-2 , -Targeted Attack (Broadsword Swing/Neck) Skill-3 , Carousing HT+1 , Cartography IQ-1 , Diplomacy IQ-2 , Hiking HT-1 , History (First Century Roman Empire) IQ , Interrogation IQ , Intimidation Will , Knife DX , Law (Roman) IQ-2 , Leadership IQ+2 , Navigation (land) IQ+1 , Politics IQ-1 , Public Speaking IQ , Riding (Horses) DX+1 , -Cavalry Training Skill-1 , -Combat Riding Skill+2 , Savoir-Faire (Military) IQ+2 , Shield DX+2 , Spear DX-1 , Strategy (Land) IQ+2 , Tactics IQ 
As a Roman soldier, Virilus gets a list of skills as matter of course: Hiking, Broadsword, Shield, Spear, and Knife. As a fighting general, though, he only seems to get much use out of his sword skill, so the others I kept at the lowest level of skill. Most of the rest of his skills are a result of his status as a general. Riding, Law, Leadership, Politics, Strategy, and Tactics all fit into these commander categories. The rest are a selection to round out his character, with Savoir-Faire (military), Carousing, and Brawling being picked specifically to aid his special rapport with his subordinates. Unlike Etain's sheet, this write-up has a specific type of skill included: Techniques. Techniques are a subset of a specific skill, and in the listings above they are marked with a hyphen and follow the skills they rely upon. Each Technique represents a 'trick' or aspect of the skill that you can train to be unusually adept at. For instance, Virilus has focused his training to be better at using sword thrusts to the vitals, so rather than taking the usual -3 to attack an enemy's vitals, he only takes a -2 penalty when performing this signature move. This is the same story for his sword swing to the neck. His Cavalry Training and Combat Riding techniques help him to keep good control of his horse while surrounded by enemies.
Clocking in at 205 points, Virilus is built with double the number of points I spent on Etain. But, with his tremendous wealth, command, and social pull, most of his points are not poured into the soldier role. Also, the nature of GURPS' brutal combat--which I mentioned in my intro to GURPS--means that the points disparity won't mean too much when the General confronts the She-wolf, even if he has superior overall abilities.