From wikipedia:
"Xander is based in part on Whedon himself, particularly in his high school years; as such, he is often the most geeky as well as witty and verbose of Buffy's characters. The character's overriding arc through the series has been his struggle towards maturity and earning the respect of others. In the canonical comic book continuation of the series, Buffy the Vampire Slayer Season Eight (2007–2011), Xander comes to achieve these goals in becoming the tactical leader of a global army of Vampire Slayers alongside Buffy."

Xander comes with Sidestep, Support, and more. And yes, he was really, really annoying in the last season.

Dial By Eric Schaen (continued below...)

From wikipedia: "Buffy the Vampire Slayer is an American television series which aired from March 10, 1997 until May 20, 2003. The series was created in 1997 by writer-director Joss Whedon... The series narrative follows Buffy Summers (played by Sarah Michelle Gellar), the latest in a line of young women known as "Vampire Slayers" or simply "Slayers".