Vaughan's Key is a plot item and key in Dragon Age: Origins.
Acquisition
Given by Vaughan in exchange for his freedom in Arl of Denerim's Estate - Dungeon during Rescue the Queen quest.
Involvement
Opens Vaughan's Lockbox in his room in the Arl of Denerim's Estate, containing 40 
.
Notes
With high enough persuasion, the Warden can convince Vaughan to hand over the key before unlocking the cell door. The Warden can then free him, leave, or kill him.