Much like Dominion, given the large number of characters that cross over from version to version, I'm just going to lump all the versions together for simplicity's sake. For now, I've just written up the personalities of Section 9, eventually I'll get to some of the baddies and other people Section 9 deals with. Depending on how picky about it you are, there are some minor, somewhat unavoidable spoilers in here, so if you don't like knowing even the smallest bit of information about the characters, go read or watch at least one of the GitS universes first.
Officially, Section 9 is an International Hostage Rescue Unit charged with identifying and eliminating sources of criminal activities, particularly in the realm of cyber-crimes. They are quite independent from the rest of the government, with the members reporting only to Chief Aramaki and Aramaki to the Prime Minister directly. This lack of oversight allows Section 9 a great deal of flexibility in what they do, sometimes sidestepping the course of strictly legal actions, when they feel it necessary. Going with the manga, Section 9 seems to be the newest in the Japanese government, and isn't contradicted(or even brought up) at all in the movie or SAC, but doesn't really seem to play a factor thanks to Aramaki's strong negotiating tactics.
Our tough as nails heroine, Major Kusanagi is the de facto leader of Section 9 when missions actually go into the field, but she's also a fair bit more than that. For most of her life she's been a full cyborg, with only her brain(and universe-dependant, her spinal column) remaining flesh and... well, flesh. Her Megatech Body Co. body, while outwardly a generic stock model, is most definitely not civilian issue, instead it's full of various military grade and illegal components, making her quite the formidable fighter(and acrobat).
In addition to her killer hardware and gorgeous body, Motoko's got brains to boot. Not just 'normal' smarts either - over a number of years she's developed her own private sort of intelligence network, with access to all sorts of information, legal or otherwise. With this network, she also has a vast array of hacking tools at her disposal, easily making her the best hacker in Section 9, though Ishikawa's no slouch about it either.
Depending on the universe, her personality varies a fair bit. In the manga, she's got a fiery temper, readily rivalling that of any number of anime heroines over the years. In the movie, she is almost always cool and collected, and rather aloof, a classic Ice Queen sort of character. Then we get to SAC, where she's somewhere in between. Usually, she maintains a cool and collected demeanor as per the movie, but she also shows a fair bit of emotion(a fairly good range of it even), and has a much more pronounced take-charge attitude than elsewhere. Thanks to this, the crew behind SAC does a wonderful job of making her into a 'real' character.
Motoko's partner in Section 9, more or less, Batou is also pretty much a full cyborg(courtesy of Megatech Body Co. of course), though he still treats his body in a very human fashion from time to time. Typically he functions as the main muscle of Section 9, both physically and with the firearms, and doing a pretty good job of it too. Formerly an Army Ranger(at least in the SAC universe), Batou's got a strong military past, bringing some sometimes scary commando knowledge and tactics to the team.
Usually he comes off rather gruff due to that past, but he also takes some enjoyment from life, both by working outand drinking(though he doesn't really need to do either thanks to his cyborg body). Get Motoko involved though and suddenly he becomes quite the concerned character. Any time she's even remotely in trouble he's worrying about her and ready to charge in to the rescue. Not that Motoko ever really needs rescuing, or would even let him protect her, but he worries all the same. There's definitely some (sexual) tension between them(moreso in the movie and SAC than the manga), but while it is often present, it isn't something that's really explored at all.
Aside from wanting him to hook up with Motoko, one of the bigger community things with Batou is figuring out how his name is supposed to be spelled, Batou or Bateau. Fortunately most people have settled on Batou, given it's spelling as such in most every official source. It still still gets brought up though because the one place where it was Bateau is the English version of the GitS movie, which is probably people's most common introduction to the GitS universe, and as such they seem to have a tendency to defend that spelling.
Leader of Section 9, mostly flesh and bone, Aramaki is highly skilled at what he does, which is getting others to do what he wants, be they members of Section 9 or the various officials of the government. Usually he stays in the background, but he's certainly not afraid to pull a gun on someone if he feels it necessary, whatever he needs to do to get the most favorable outcome. Given how rough he handles the members of Section 9 sometimes, they have a tendency(at least in the manga) to try and pull little stunts on him, and refer to him disparaginly as "Ol' Ape Face."
Although they never particularly go into it, Motoko and Aramaki seem to have some sort of a history with each other, indicated rather early in the manga. Aramaki - "You'll identify the source of criminal activity and eliminate it. It's the sort of offensive unit you and I have dreamed of for years... But now it's up to you and your men." Given that last sentence, I've always assumed the two go way back, to when Aramaki was still a young man that could have readily participated in such operations. Since their two Bios always seem to have the most classified information, this all suggests to me they had been doing some black ops stuff together, though not on terms they particularly desired.
The 'Rookie' in Section 9, Togusa's only been with them for a relatively short period of time(depending on universe, of course), but spent years as a detective with the regular police. In addition to his strong detective instincts, Section 9 also picked Togusa for the team in part due to his being mostly flesh and bone like Aramki. Essentially this helps round out the perspective on things within Section 9, spotting things that would matter to 'normal' people that a squad full of cyborgs might miss. He's also a family man, unlike the rest of Section 9, which brings yet more perspective to the team.
While he sometimes suffers bouts of uncertainty after making a mistake or getting into something he doesn't have a firm grasp of understanding on, he's fairly competent in the preformance of his duties. Part of that is that he's still relatively new to the job, and not necessarily comfortable with all the things that they do, but it's also probably due to an awareness of his own mortality, and that he has a family to be thinking about.
A bit of an idiosyncracy, Togusa almost always uses a 6-shot Mateber revolver instead of Section 9's standard Seburos. While he is trained in both, it's certainly his preferred firearm, and something he catches flak on from time to time. So far as he's concerned, the Seburos are overkill, and he's got plenty of stopping power with the revolver, so he doesn't carry the larger Seburo.
Specializing in Information, Ishikawa is the last of the Section 9 members that gets any sort of focus. Not that he gets a whole lot, mind you, but still more than the guys below. He's regularly shown digging up some information that the rest of the team needs, staying in the background usually. Unlike Aramaki though, he does go out and participate in the field ops if necessary. Like Motoko, he also does some stuff outside of the law, such as running a cyber-Pachinko parlor and tapping the player's brains for processing power, like a little brain farm/supercomputer.
The Big Silent Guy of Section 9, he's the other main brawn of the team. Unfortunately he gets very little action, though he does get to use The Big Gun, and causes 'accidents' for certain people, in addition to the regular team field ops. Being such a minor character, he was completely excluded from the GitS movie, and while he shows up some more in SAC, he really doesn't do much. Actually, given one of the later episodes of SAC 2nd GIG, it seems he has some skill with defusing bombs. He also seems to accompany Aramaki in GitS: MMI(I'd thought it was Batou for the longest time, but the red eyes and baldness really should have tipped me off sooner).
Like Batou, Boma's suffered from a variety of names. Worse than Batou really, I've seen his name spelled as Boma, Borma, Booma, Bouma, and I think one or two more variations thereof. Fortunately the official English translations seem to stick with the nice and simply Boma.
Initially just another member of the team, Saito never really had any sort of presence until SAC, where they turned him into the team sniper. While he really doesn't do a whole lot aside from that, he is one of the cooler looking members of Section 9, with his wicked looking 'eyepatch.' Like Boma, no movie appearance for him.
Yay, least character development ever. Best guess I have is that he used to be some sort of mobster/Yakuza that got recruited by Aramaki/Motoko for his talents. Not that we have much clue about his talents, but he's quite the shady looking character. About midway through 2nd GIG, they finally give him some backstory, seems he's quite the ladies man, sleeping with many of them, and never the same one twice, doesn't tell us his specialty at all, but its still something. Again, a no-show for the movie.
Now here's some personality and development! The Fuchikomas(manga) and Tachikomas(SAC) are Section 9's smart tanks, small, insect-like, and very mobile. Just to clear things up, while they're Fuchikomas in the manga universe and the Playstation game, Oshii never brought them into the first movie, and when it came time to make SAC, there were copyright issues that came up, preventing Production IG from using them in the series. Thus the typically red Fuchikomas transformed into the slightly different, blue Tachikomas. Most noticeably they changed the shape of the back segment where the driver sits, but they also reworked the 'face' a fair bit, switching from the bars and lenses to the triple chameleon eyes.
The most endearing part of the 'komas is their AI, extremely naive and innocent, and bubbling with a child-like energy. Which is strange for me, because normally I really don't care for energetic children, slap that personality into a little death machine and I'm all for it though. This childlike AI makes for some interesting interactions within Section 9- Batou really likes them, and tends to stick with a particular unit and likes to give it little presents, whereas Motoko inherently distrusts them because of their personality, which she feels will lead to a major problem in the field when their attention gets sidetracked.
Stemming from the short(4-pages!) Rise of the Machines chapter in the original manga, Production IG has given the world a great treat in the form of Tachikoma Specials at the end of each episode of SAC. These are little 3-minute shorts featuring the Tachis conversing absurdly and doing silly things, like playing catch with their antennae and showing off their upgrades. And even more fortunate for us, these shorts are going to be included on the Region 1 DVDs. If you're looking for animated Fuchikomas however, your only real recourse is to track down the GitS Playstayion game, where you spend the entire time driving one, and then get to watch them in full animated glory during the cutscenes.
Of course, there's a number of other people and groups that Section 9 has to deal with, enough so that I could go on all day just with some of the more interesting 1-episode characters in the two seasons of SAC, but I'll just highlight some of them after covering the important people.
Prime Minister Kayabuki: After the events of Season 1, Japan's Prime Minister is ushered out of office and Kobayaki is elected in in his place as someone who doesn't have a hint of scandal associated with her and willing to talk about the hot-button refugee issue. While she is the Prime Minister, many in the government view her as little more than a figurehead and treat her as such. Much to their chagrin, she won't be pushed aside so easily and continuously fights to get her agenda pushed through. Unlike most politicians, she's clean, honest, and willing to not play by the rules, earning her Aramaki's confidence, friendship, and sympathy for what she has to deal with.
Cabinet Intelligence Agency: The newest agency within the Japanese government, the CIA is comprised of several older intelligence groups and essentially fights terrorism, rebellion, and similar issues, purely through information warfare. They manipulate groups with false or misleading information, bury truths they don't want others to see, and break into other information systems to find out what others are doing/planning with no apparent limitations. As this is extremely similar to what Section 9 does, we find a major rivalry start up when they first show up here in 2nd GIG.
Goda/Gohda/Gouda: Head of the CIA, this guy becomes Irritant Number One to Section 9, either stringing them on to get something done for him, or overtaking something they were working on, or outright beating them to the punch, and he's always happy to do so, as he loves to manipulate the flow of information. He's also extremely visible, sporting a huge facial scar that severely twists his face, having opted to never have artificial restoration or cyborgization done to it.
Individual Eleven: Revolutionaries/terrorists taking their name from a group of people who participated in a Japanese rebellion in the early 1900s, though they are apparently without orginization. Either in small groups or as individuals, these people cause a number of terrorist attacks that are aimed at inflaming growing tensions between the Japanese citizens and refugees who have been living in the country since the end of World War IV. The lack of organization initially has Section 9 looking for a virus or something similar to what caused the string of Laughing Man incidents, but as the show progresses we find out its something on a whole different level altogether.
Kuze: A full-body cyborg that is initially a member of the Individual Eleven, we first meet him as he makes an attempt on Prime Minister Kobayaki's life, is stopped by Section 9, and manages to escape before they can catch him. At first, he seems to be just another random member of the Individual Eleven, but as the story progresses, he evloves into one of the major characters for the season, going so far as becoming a hero to nearly the entire refugee community. On top of that, we also get a lot of backstory on him that does a wonderful job of developing the character(but I don't want to spoil the surprise).
Proto/Puto/Pluto: Starting out as one of Section 9's red-suited technicians, but eventually moving into more of an assistant role to Aramaki, he's the only person to get much screen time as a new member of Section 9 this season, and also appears in GitS 1.5
Yazuma + Yano: These two are new recruits to Section 9 that originally appeared in the GitS mangas, Yazuma as Batou's new partner in 1.5 and Yano as a footnote of a character in the original GitS manga. Unlike Proto though, they serve as additional field members to give the team more muscle. Unfortunately we don't get to find out if they bring anything else in particular to the team, even though they show up in 4-5 episodes with a moderate amount of screen time.
The one-ofs in this season were just as diverse, with a disabled refugee constantly dreaming of fantasy scenarios involving him doing something heroic/sacrificial for the love of the purple-haired woman his sees and longs for, a teenage boy getting himself involved with the Chinese mob that spends a night with Motoko, one of Paz's former lovers spurned and seeking revenge, some of the wealthiest people in the nation that have expensive parties for their android fetishes, and a woman that may know something of Motoko's past.