Dawn Summers is a fictional character created by Joss Whedon and introduced by Marti Noxon and David Fury on the television series Buffy the Vampire Slayer, portrayed by Michelle Trachtenberg.

Within the series, Dawn is the younger sister of main character Buffy Summers (Sarah Michelle Gellar), a girl chosen by fate to be a vampire Slayer.

The show's sixth and seventh seasons, as well as its canonical comic book continuation, follow Dawn's journey toward adulthood.

When Dawn learns of her origin, she resorts to self-harm and runs away from home, until Buffy assures her they are real sisters no matter what, securing it with a blood oath.

It is eventually revealed that Dawn's purpose as The Key is to open portals to alternate dimensions — a power the hell-god Glory wishes to exploit to return home.

Having been devastated by her sister's death, Dawn is overjoyed when Willow (Alyson Hannigan) casts a spell to bring her back to life.

However, with Buffy spiraling into a deep depression, Dawn feels highly neglected and is often seen alone and seeking attention from her sister, as well as other members of the group.

Dawn's isolation from the other characters reaches its apex in "Older and Far Away," when she inadvertently makes a wish to the vengeance demon Halfrek (Kali Rocha), which results in trapping everyone who enters the Summers house.

Halfrek herself is inadvertently trapped, and undoes the curse to free herself; meanwhile, Dawn's kleptomania and feelings of neglect by her friends and family are exposed.

Dawn then falls into a watcher-esque role offering the group answers from research, such as ways to communicate with The Bringers and translating texts given to Buffy in a 'slayer keepsake'.

When Buffy tricks her into leaving town before the impending apocalypse, Dawn adamantly returns to fight against the First, during which she battles alongside Xander, and once again proves her value as a fighter by killing several Ubervamps and survives.

Dawn was intended to appear in the Angel episode "The Girl in Question", but Michelle Trachtenberg was unavailable for filming, so Andrew Wells (played by Tom Lenk) replaced her.

While her personal issues are made to take a backseat with Buffy, in battles, her gigantism shows some utility; she is able to assist fighting Amy in "The Long Way Home", and rampages through Tokyo to distract their enemies in "Wolves at the Gate".

In the series' final arc, Buffy brings about the end of magic, following which Xander and Dawn decide to settle down in San Francisco.

In final arc "The Core", Buffy, Willow and Xander head to the Deeper Well in England in hopes of finding enough magic to restore Dawn.

After the gang restart magic, they return to San Francisco where Willow is able to bring back Dawn using Buffy's blood in conjunction with the spell which created her.

"[4] Trachtenberg says she was thrust into the role without knowing much about Dawn's personality; she describes her initial meeting with Joss Whedon as "Alright, welcome to the cast, you're a teenager, you're a Key, have fun.

She praises the character for taking charge and accepting the possibility she might be a Potential Slayer, and for quietly stepping back when she turns out to be wrong, without revealing how disappointed she really is.