Alexander LaVelle "Xander" Harris (1981-?) is a resident of Sunnydale and ally of Buffy Summers. He has served her crusade against evil, more often than note helping on the sidelines, but Xander has played a significant role a few times.
Xander met Buffy when she transferred to Sunnydale High School sophomore year. He was best friends with Jesse and Willow Rosenberg. Jesse was captured by vampires and turned. Following a confrontation, he was staked by Xander.
Xander, Willow, and Buffy's Watcher Rupert Giles aided Buffy in fighting supernatural forces. Xander wasn't a fighter and didn't possess any supernatural power or skill, so his primary role was helping them research.
A spell by Ethan Rayne during Halloween of 1997 turned Xander into the costume he was wearing at the time, that of an army soldier. Following the incident, Xander retained some military knowledge, which made him Buffy's key in coordinating an attack against The Mayor
Xander began a romance with classmate Cordelia Chase his junior year. This romance wasn't long-lived, as Cordelia caught Xander kissing Willow, and their relationship dissolved.
Upon graduating high school, Xander attempted a cross country trip that didn't go as planned. He returned to Sunnydale in the fall of 1999 to once again help Buffy. His prom date, ex-demon Anya also returned to Sunnydale, and after some awkward and strange moments, they began dating.
While his friends attended college, Xander floated from job to job. He worked as a hotdog vendor among others. When a rift formed between him, Buffy, and Willow, he considered leaving Sunnydale and joining the army. The rift was repaired, however, and Xander took part in a spell to increase Buffy's powers to fight Adam. Xander eventually found a job as a construction worker and finally moved out of his parent's house.
Soon before Buffy and the gang fought Glorificus, Xander proposed to Anya. Buffy's death and eventual return made Xander hesitant to tell his friends about their engagement, but when he finally did, they all supported him. On his wedding day, Xander met a demon claiming to be him from the future. This put enough doubt in Xander's mind that he called off the wedding between him and Anya. Although they never got married, Xander and Anya continued to care deeply for one another.
When Buffy took all the potential slayers in to train them, Xander helped house them and took part in their education. During a battle against The First's forces, Xander's left eye was poked out by Caleb. Xander spent some time in the hospital recovering and was able to join Buffy for her last battle. He survived, although Anya did not.
With Sunnydale destroyed, Xander took part in re-forming the Watcher's Council, going to Africa to presumably find and recruit Vampire Slayers.