I don't think any journey through the Buffyverse could be complete without our next guest. I'm not even sure he needs a lengthy introduction. So with no further ado, may I present to you, one of the sexiest librarians around, Mr. Rupert Giles (Ripper to his friends).
Theoretically, if I were a young teenage girl charged with the slaying of vampires and other demons, I would want someone like Rupert Giles to be there for me. When Buffy first arrives in Sunnydale, trying to put her slaying days behind her, she realizes that not only can she not escape her destiny, but she also has a new Watcher. Giles is a third generation Watcher and even though he tried to get away from it in his youth, going as far as demon worship, he found himself in the same shoes as Buffy. He was destined to be someone he didn't want to be. Also like Buffy, once he accepted his destiny, he excelled at it.
On the surface, Giles didn't seem all that impressive. He came across as rather mild mannered, a bit nerdy (despite the good looks), and way too stuffy. Underneath all of that though lurked a dangerous man, one that you did not want to be on the bad side of. When he needed to, Giles was capable of a detached sort of violence that none of the other characters came close to. When he smothered Ben, so Buffy would not have to, he showed a side of him that I think had been hinted at all along but was rarely shown in such a blatant way.
He was also proficient in both hand to hand combat and magic. He taught Buffy all she needed to know in order to defend herself and slay anything that made it's way to the Hellmouth. With the magical training of Willow, things didn't run as smoothly. Giles was totally against her involvement from the beginning, but when he realized she would progress without him, into dangerous waters, he took her under his reluctant wing and taught her what she needed to know. In fact, overtime, the pupil outpaced the teacher and I don't think he could have been prouder or either one of them.
I think of all the characters, Giles was the most subtly complex of the lot. Where a lot of them wore their personalities on their sleeves, Giles did more of a slow reveal of himself. I don't think he showed off every facet of himself until well into the 6th season. Regardless of his mistakes, which he did make a few of, Giles was a true father figure to The Scooby Gang. He loved them and tried to protect them the best he could in a world where any of them could be killed on any given day. He was a fabulous mentor and friend to them all and I have to admit to being a bit jealous of them for that.