Sean made a number of good points in his post on Warrior archetypes, and I have no beef with anything he said. However, I do have a couple of other archetypes that could be added.
The Career Soldier. Whether s/he got into it because they believed in the cause, wanted to get away from their home or thought there was some honour to be had there, this character entered the army years ago and sticks with it because they want to see where it takes them. They probably don’t like killing people, but it’s a necessary part of their job. The thought constantly on their minds will probably be promotion; they probably wouldn’t still be there if they didn’t think there was some honour and recognition to gain out of it, it’s long past that. They almost certainly do everything by the book – after all, they won’t get anywhere by disobeying orders or acting inappropriately. (The most obvious spec for this is Arms. They know how to fight, they know how to kill people more quickly and efficiently, and they’ve gotten awfully good at it over the years.)
The Patriot. When they heard that there was a foreign menace threatening their way of life, they stood up and said, “I will not let this happen to my people!”. Whether this is actually by enlisting in the armed services, or by going off by themselves on an adventure, their focus is on defending their people (despite the name I have given them, it may not necessarily be their country; it may be their village or even their family), and they will do anything to achieve that goal. They might be seen as more reckless than the Career Soldier, and certainly more so than the Stoic, and depending on type, they will either have a lot more or a lot less respect for the authority. They may be of the type that thinks that their country and, by extension, the laws set down, can do no wrong. By stark contrast, they may believe that the most important thing is defending their people and smiting the enemy, and if this means a few pesky rules have to be broken on the way, then so be it. (Spec uncertain; Protection or Fury, possibly, but it’s more up to you.)
The Fat, Jolly Badass. When you meet them, they seem like a jovial sort – they’re probably drinking beer, smoking cigars and eating to excess, generally being a bit of a glutton, but in an entirely likeable way. When they start to talk about their war stories, you just can’t believe that such callous (if necessary) things have been done by this jolly old chap. When you see them in battle, they face it with grim necessity, right up until one of their mates (or, more likely, one of their subordinates) gets attacked, at which point they step right over and skewer the bastard who did it without even a second thought. They will defend those who depend on them, viciously if necessary, and without regret, and as soon as the battle’s over they’ll happily sit down and have another smoke. Everyone seems to owe them a favour, and they’ve been a fighter for most of their life, and yet you’d never guess it from how jolly and personable they can be. Of course, jolly fat men are funny, and you don’t take funny people seriously in a fight… (Again, spec is a bit less certain, but I’d recommend fury; they can anger quickly under the right circumstances and bursts of rage get them through battles just as much as talent. Arms would also be a good choice, as they’ve clearly been working on efficient ways to kill people most of their lives.)