**Pål Tverdal Mathiesen**, also known by artist names such as "Athera", "Shady Blue" and "Daukjött", is a Norwegian vocalist, drummer and voice actor.
He has been a member of bands such as Vanaheim (1998), Metadox (1992–1994), Red Light Territory (1994–1995) and Ringnevond (1999), and is now a vocalist in the thrash metal band Susperia, and the Heavy rock band Chrome Division.
