|This article is about the the Key in its original form. For the being into which the Key was transformed, see Dawn Summers.|
- "The Key is the link. The link must be severed. Such is the will of God."
- ―Litany of the Knights of Byzantium[src]
The Key was an ancient mystical energy with the power to unlock the gates between all existing dimensions, though only at a certain time and place.
Who, when or why it was created is unknown, though in the 12th Century, the Order of Dagon was founded by Tarnis in order to protect it. Meanwhile, the Knights of Byzantium sought to destroy the Key so its destructive power would never be unleashed. While one of the monks claimed that for centuries the key had no form, Glorificus, having seen the Key very briefly, described it as "a bright, green, swirly shimmer".
In 2000, fearing that Glory would use the Key, the surviving monks of the Order of Dagon transformed the Key into Dawn Summers with the hope that Buffy Summers, the Slayer, would keep it safe. Reality was altered and Dawn and everyone around her were given false memories so that they would believe she had always been present as Buffy's younger sister. The monks used Buffy as a template to create Dawn's physical body, making them biological sisters. However, people "beyond reality," such as the mentally ill, were able to perceive Dawn as the Key. Since Glory created a stockpile of these individuals, unaware of what they were capable of for months until eventually one of them identified the Key in Glory's presence, leading to her capturing Dawn the night after.
In 2001, Glory's worshipper Doc succeeded in using Dawn as the Key by spilling her blood, but the resulting tearing of the veils between dimensions was soon sealed back by Buffy's self-sacrifice.
Following Glory's defeat
Following these events, Dawn herself stated that, to the best of her knowledge, she was no longer the Key, and even if she was, she no longer opened anything, while Andrew Wells stated that she used to be the Key; however, Dark Willow's threat to turn her back into an energy ball called this into question.
After the destruction of the Seed of Wonder and the subsequent loss of magic Dawn has been shown to be 'breaking down', being physically weak and occasionally turning intangible as others' memories of her are lost, but it is unclear if this means that she is turning back into the Key or if it is simply the breakdown of the spell that created her.Lately Dawn discovered she was the The Key all along and more importantly she didn't need a ritual to access her powers she just just believed in her self and had some courage and faith from her sister and the others dawn accessed her powers that now she can open portals to any dimension and destroy the barriers that holds them which can lead to an apocalypse,she can shrink and destroy powerful demons with a flick of her wrist and can even do a Force field in order to protect herself and others Giles implied that Dawn had become god like entity.
- "No Place Like Home" (Only in flashbacks)