Pål Mathiesen (born on 14 August 1977), also known under the stage names Athera and Shady Blue, is a Norwegian singer, best known as the former lead vocalist of the black/thrash metal band Susperia.

He is also the former lead vocalist of Chrome Division and a session live vocalist in Borknagar.

In 2009, Athera suffered a heart attack which resulted in major open-heart surgery.

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