Thaleen appeared in the Farscape episode "Rhapsody in Blue".

She is a Delvian priestess. After her father Tuzak went insane, she became the leader of a small group of Delvians that are trying to develop their powers so they can use them as weapons against the Peacekeepers. The problem with that is that the use of the power for causing pain, increases the chance of going insane. She used her powers to lure Moya and it's crew to the planet with the purpose of getting the control that Zhaan has mastered.