Lilley is a warrior employed by the Coterie.
Lilley is involved in the quest Inside Job.
Hubert Bartiere brings her along to hear Sabin's confession, after which she offers to kill Sabin (the choice is up to Hawke). Lilley then takes Hawke outside Kirkwall to eliminate the bandits who were raiding the Bone Pit's caravans.
After the battle, Lilley recognizes one of the bandits as a thug working for Brekker. Since Brekker also works for the Coterie, she leaves to investigate it and arranges to meet Hawke in the Undercity. Hawke arrives to the meeting place only to find Lilley dead, and a group of Coterie thugs confronts Hawke about what happened. Hawke has the option to tell them that Lilley was murdered by Brekker or can simply kill them.