I will start by talking about a few of his major characters.
Rincewind. I'm going to barrow a little from The Discworld Companion. A wizard. At least, generally referred to as a wizard.
"He is tall, thin and scrawny, with a raggedy beard that looks like the kind of beard worn by people who aren't cut out by nature to be beard-wearers.
"He is a survivor. There are scars all over him. Mostly on his back.
"Around his neck is a chain bearing the bronze octagon which marks him as an alumnus of the Unseen University (quite wrongly, it must be pointed out, since he has never passed any kind of magical exam. Indeed, he never scored more than 2% in his exams, and that was for spelling his name almost right)."
On his head is a battered pointy hat with a floppy brim, which has the word 'WIZZARD' embroidered on it in big silver letters by someone whose needle work is even worse than their spelling.
He does have an innate gift for languages, which enables him to shout 'Don't kill me!' and be understood in a hundred different countries. He is also good at practical geography, which means that he always knows exactly where it is he is running away from.
His current whereabouts are in doubt, but owing to some error on the part of the wizards who tried to teleport him back to UU, they (his whereabouts) are believed to have a certain boomerangy, didgeridooy quality. You get the idea. He is someone who would love to be board all the time. His one accomplishment seems to be the fact that he did stop the most powerful wizard on the planet with a sock that had a brick in it...Well, he didn't really win, but the other wizard didn't win either.
Commander Samuel Vimes
Head of the Ankh-Morpork City Watch...An upright and honest man whose appointment to the despised Night Watch–regarded by all sensible people as a completely useless appendage to the running of the city–may have been the cause of his drinking problem. But it has also been suggested that he is in fact naturally more sober than other people. (Now I have to put in something new called KNURD: KNURD is the opposite of drunk. It is not sobriety. Sobriety is merely the median state; knurdness is a sort of super-sobriety. By comparison, sobriety is like having a bath is warm cotton wool.) A state of acute sobriety is not one in which a man would like to view the society of Ankh-Morpork and he naturally sought to ameliorate this with a drink or five, and got the number wrong. It is known that he was born in Cockbill Street in the Shades, that his father was Thomas Vimes and his grandfather Gwillaim Vimes. Membership of the Watch was a family tradition and Samuel would have joined shortly after leaving school had he ever gone to school.
He is almost certainly one of Nature's policemen; it has been said of him that his soul burns to arrest the Creator of the universe for getting it all wrong.
He loathes kings, and hates undead and assassins. He is also unashamedly speciesist – he deeply dislikes trolls and dwarfs, but in an almost proprietorial way, so that he has risked his life and badge to defend them merely so that he can continue to dislike them.
Married to Lady Sybil Ramkin, he was promoted to commander, and knighted against his will. He is now a Duke, but only by some clever bribing (on the part of other people bribing him to become Duke).
'Old Stoneface' Vimes
Former Commander of the City Watch who beheaded - because no one else would do it - the last King of Ankh-Morpork, Lorenzo the Kind. It is thought that he may well have been a relative of Sam Vimes. This possibility, we suspect, is one secretly cherished by Sam Vimes. This act of regicide was followed by six months under the rule of Stoneface and his efficient if unimaginative soldiers known as the 'Ironheads'. Samuel Vimes embraces the cynical belief that Old Stoneface tried to introduce democracy to the city and that the people voted against it.
Carrot Ironfoundersson.
A dwarf (by adoption). His adoptive dwarf parents found him in the woods as a toddler, wandering near the bodies of his real parents, who had been victims of a bandit attack. Also in the wreckage of the cart was a sword, and a ring that was very similar to one recorded as haveing once been a part of the rayal jewellery of Ankh.
When first encountered he was 6' 6" tall and nearly sixteen years old with a big, honest forehead, mighty neck and impressively pink skin, due to scrubbing.
When Carrot flexes his muscles, other muscles have to get out of the way first. He has a punch even trolls have learned to respect. He walks with a habitual stoop, which comes from being 6 feet tall while living with dwarfs (average hight 4' 4").
His parents, embarrassed at his size and by the fact that he reached puberty at what in dwarf terms is about playgroup age, realized that he needed to be with his own kind. They arranged for him to join the Night Watch in Ankh-Morpork because, they had been told, it would make a man out of him.
In his whole life, before coming to Ankh-Morpork, on one ever really lied to him or gave him an instruction that he wasn't meant to take literally.
He is direct, honest, good-natured and honourable in all his dealings. Despite his service in the Watch he still thinks everyone is decent underneath and would get along just fine if only they made the effort. He belives this so much that other people start to belive it too. To not would be like kicking a puppy.
Angua
Constable of the City Watch. Her full name is Delphine Angua von Uberwald. Her father (sire) was Baron Guye von Uberwald (also called Silvertail); her mother was Mme Serafine Soxe-Bloonberg of Genua (also called Yellowfang). For most of the month she is a well-developed girl with ash-blond hair. At full moon she is a werewolf with blond hair as long as a mane around her ears. Angua forms a liaison with Corporal Carrot Ironfoundersson. well, a bit more than just a liaison. It appears that Carrot had been more than happy to forgo the slight monthly dampener on the relationship in exchange for a girlfriend who is always ready for a nice long walk.
Only two more to go, and I have all ready written 1,140 words.
Foul Ole Ron.
A member of the Beggars' Guild. He is a Mutterer; he walks behind people muttering in his own private language until they give him money not to. His familiar phrases included 'Bug'r'em', 'Bugtit' and 'Millennium hand and shrimp'. People assume that Foul Ole Ron has no grasp on reality but this is not true. He holds very tightly on to reality, but it is not the one shared by the rest of the world.
Foul Ole Rons' Smell
Foul Ole Ron is often but not always accompanied by his Smell, which has become so powerful over the years that it has developed a life of its own and often goes about its own occasions in the city without its theoretical owner. It is in fact rather more socially aware than Ron, and has been know to attend the opera while Ron is enjoying a meal of old boiled boots several streets away. The smell has even passed beyond the smell barrier. You can now sense it not by smelling it, but by how your earwax melts.