Nicholas Brendon was born Nicholas Brendon Schultz on April 12, 1971 in Los Angeles, three minutes after his identical twin brother, Kelly Donovan.
At the age of 25, Brendon decided to return to acting. He signed with a manager and obtained the role of Xander Harris on Buffy the Vampire Slayer three months later. He appeared in all but one of the 144 episodes in the series, and even shared the screen with his twin, Kelly Donovan, when his character was split in two in the fifth-season episode "The Replacement."
Brendon has done work for the Stuttering Foundation of America, which approached him around 2001, and made him its honorary chairperson for its National Stuttering Awareness Week in May 2001, May 2002 and May 2003.
After the series ended in 2003, Brendon joined the cast of the Fox television pilot The Pool at Maddy Breakers. The series was not picked up by the network. In 2004, he co-starred in his first ABC Family movie, Celeste in the City. The following year, he returned to Fox as part of the cast of Kitchen Confidential, based on the book by chef Anthony Bourdain. Thirteen episodes were made, but the series was cancelled on December 9 of the same year, after the fourth episode aired with low ratings.
In 2006, he voiced Huntsboy #89 for season 2 of the animated series American Dragon: Jake Long. That same year, he reunited with his former Buffy the Vampire Slayer co-star Charisma Carpenter in the ABC Family TV movie Relative Chaos.
From July 26 through August 30, 2006, Brendon co-starred with Noah Wyle in the play Lobster Alice at the Blank Theatre Company in Los Angeles. He subsequently appeared in the Blank Theatre's annual Young Playwrights Festival and its productions of The SantaLand Diaries (November 20–December 20, 2009), and Why Torture Is Wrong, and the People Who Love Them.
In 2007, Nicholas began appearing on the TV series Criminal Minds in the recurring role of FBI technical analyst Kevin Lynch. He has appeared in episodes in each season since, through the seventh-season finale in 2012.
On September 29, 2010, he premiered his web comic Very Bad Koalas, co-created with animation director/producer Steve Loter. The comic follows the journey of two sheltered and innocent koalas experiencing a variety of people and places while on the run from the law in a 1958 Cadillac El Dorado.
On October 28, 2010, Brendon began a four-episode arc on ABC's Private Practice playing Lee McHenry, a mentally disturbed man who assaults Charlotte King.
On 2014, Brendon was part of a summit for writers of Buffy the Vampire Slayer comics, which included Joss Whedon, Jane Espenson, Drew Greenberg, Andrew Chambliss, and Christos Gage. He was involved with the show's canonical comic book series Buffy the Vampire Slayer Season Ten, on stories centering on his character.
Beginning in 2019, Nicholas discovered painting and is now offering artwork, photography, and merchandise under the "Slightly Askew by Nicholas Brendon" label.
Brendon currently has a recurring role as Chief Engineer Britman in the adventure sci-fi web series Untitled Web Series About a Space Traveler Who Can Also Travel Through Time.
Brendon has struggled for many years with depression and alcoholism, leading to many run-ins with the law and multiple arrests and several convictions for destruction of property, vandalism, theft, and domestic violence.
Brendon appeared in every Buffy the Vampire Slayer episode, except for "Conversations with Dead People." He was present as well in the unaired pilot, already in his role as Xander. Brendon portrayed him as well in the Buffy ad campaign Halloween Bash, in partnership with Barq's root beer. Additionally, he portrayed the vampire counterpart Xander from an alternative timeline in the episode "The Wish."
- Buffy the Vampire Slayer pilot
- Buffy the Vampire Slayer season 1
- Buffy the Vampire Slayer season 2
- Buffy the Vampire Slayer season 3
- Buffy the Vampire Slayer season 4
- Buffy the Vampire Slayer season 5
- Buffy the Vampire Slayer season 6
- Buffy the Vampire Slayer season 7 (Credited but does not appear in "Conversations with Dead People")
Brendon co-wrote the following Buffy the Vampire Slayer Season Ten issues, with Christos Gage:
- New Rules, Part Three
- New Rules, Part Four
- New Rules, Part Five
- I Wish, Part Two
- Love Dares You, Part Two
- Love Dares You, Part Three
- Freaky Giles Day
Brendon appears in the following Buffy the Vampire Slayer featurettes:
- "Designing Buffy"
- "A Buffy Bestiary"
- "Beauty and the Beasts: Behind Buffy's Makeup"
- "Season 3 Overview"
- "The Sets of Sunnydale"
- "Season 5 Overview"
- "Behind the Scenes of 'Once More, with Feeling'"
- "Buffy Abroad"
- "Buffy Wraps"
- Audio commentary for "Dirty Girls"
Behind the scenes for Buffy the Vampire Slayer and Angel.
- Gary Susman, "Buffy's Xander checks himself into rehab." EW.com, April 30, 2004.
- Karl Etters, "Buffy the Vampire Slayer actor Nicholas Brendon arrested." Tallahassee Democrat, March 14, 2015.
- Mike Moody, "'Buffy' star Nicholas Brendon 'arrested.'" Digital Spy, March 18, 2010.
- Helen Nianias, "Nicholas Brendon: Buffy The Vampire Slayer actor arrested for trashing Hilton hotel room and not paying the bill." The Independent, February 18, 2015.
- Alex Stedman, "'Buffy the Vampire Slayer' Actor Pleads Guilty After Allegedly Choking Girlfriend." Variety, December 6, 2015.
- Natalie Stone, "Buffy the Vampire Slayer Actor Nicholas Brendon Charged with Domestic Violence." PEOPLE.com, May 6, 2019.