When Benjamin Locke was hiding in the caves with the revolutionaries, they accidentally opened the Black Door allowing the Children of Leng to escape. Once Benjamin realized that regular steel was insufficient to hold the door closed, he crafted a padlock and key from Whispering Iron which proved sufficient to hold the door shut. Later, the lock was modified to be part of the door itself.
The key was only used to obtain Whispering Iron, and no infestation of the Children of Leng was recorded until the Tamers of the Tempest made their attempt to open the Black Door. After the events of that attempt, Rendell Locke vowed to ensure the Omega Key would stay hidden for the rest of his life.
When Dodge returned, he started hunting for the Omega Key, which had been concealed in the urn containing the cremated remains of Rendell. After the urn was shattered, Tyler and Kinsey Locke rediscovered the Omega Key. Tyler attempted to hide the Omega Key in his head using the Head Key, but when he was infected with Kinsey's Tears and Fear, his siblings opened Tyler's head to remove them and Dodge (in Bode Locke's body) found the Omega Key, removing it when the others were not looking. Dodge used the key to open the Black Door, and had selective demons infect various students during the Locke after-party in the Drowning Caves.
After Dodge's defeat, Tyler kept the Omega Key on a keychain, with most of the other keys.
After witnessing the portal that was opened by Captain Frederick Gideon and the danger that had come out of it, Benjamin Locke seeks to seal it behind the Black Door and to use the Whispering Iron from a demonic bullet that narrowly missed him and his sister to make the key. However, Benjamin's attempts fail until Miranda recalls that in alchemy, one must have both intention and sacrifice. By adding his own blood to the molten metal, Benjamin succeeds in crafting the Omega Key and sealing the portal behind the Black Door. His success and the Whispering Iron on the cave floor peaks Benjamin's interest into what other kinds keys he can make.
In 1988, the Keepers of the Keys use the Omega Key to open the Black Door, resulting in Lucas Caravaggio getting possessed by the demon Dodge. The other Whispering Iron that was left behind when the door was opened is later used by Duncan to create the Memory Key.
When the Keepers split up the keys, Rendell takes the Omega Key which he subsequently hides inside of his own head using the Head Key. After Rendell's death and cremation, it ends up in his ashes where its later found by Tyler and Kinsey Locke.
After the apparent defeat of Dodge, the Savini Squad uses the Omega Key to send the demon back through the Black Door, although Eden gets possessed in the process. Unbeknownst to them, it was actually Ellie Whedon that they had sent through the door, disguised as Dodge with the Identity Key.
The key is the only key able to open the Black Door. Other than this, it also follows the intent of its creation and prevents any other key from opening the way to the Children of Leng. Any attempt to open the door using other keys will just open into an empty room.
Guide to the Known Keys entry
(damaged) "...another dead & the...dore open againe...the things turned to
irone...in our w...& I resolved to use them to crafte...hazzarded such a lock wood hold...long I worked in a fever'd...till finallie t'was cast &...oh how I feer'd! My har...in the gathr'd dark... straiked out &...held the dorr...beig'd God... Gonel...hold"
- This key and its counterpart, the Alpha Key, were created in reverse order. As has been stated, the Omega Key was created first, and the Alpha Key was created last, about 237 years later.
- JOE HILL, GABRIEL RODRIGUEZ, and CHRIS RYALL for Locke & Key — July 2021 Masterpiece Selection
- Locke & Key: Clockworks #1, "The Locksmith's Son". July 20, 2011
- Locke & Key: Clockworks #4, "The Whispering Iron". February 1, 2012
- Locke & Key: ...In Pale Battalions Go... #1. August 26, 2020
- Locke & Key: Clockworks #3, "The Tamers of the Tempest". December 14, 2012
- Locke & Key: Clockworks #6, "Curtain". May 16, 2012
- Locke & Key: Crown of Shadows #6, "Beyond Repair". July 14, 2010
- Locke & Key: Clockworks #2, "Smash!". August 31, 2011
- Locke & Key: Alpha #1, "Omega & Alpha", September 11, 2013
- Locke & Key: Alpha #2, "The End", December 18, 2013
- Locke & Key, Season 2 Episode 9: Alpha & Omega
- Locke & Key, Episode 9: Echoes
- Locke & Key, Season 2 Episode 3: Small World
- Locke & Key, Episode 8: Ray of F*cking Sunshine
- Locke & Key, Episode 10: Crown of Shadows