Swedish terrorist group
better known as the foes of the SAS
and other counter-terrorist outfits in the game Counter-Strike
Nobody really knows what these frosty folk are supposed to be avenging. They were formed in 1977, in a period of Sweden's perpetually peaceful history when people danced to ABBA and their welfare state actually worked. But something obviously riled them enough to blow up the Canadian embassy in Stockholm in 1990 (perhaps something to do with ice hockey).
The Arctic Avengers are known to always wear white anoraks, even when carrying out operations in Italian villages or Aztec temples.