Kopparberg is a locality and the seat of Ljusnarsberg Municipality, Örebro County, Sweden, with 4,200 inhabitants in 2015. It is famous for one of the most valuable postage stamps in the world, the Treskilling Yellow from 13 July 1857, Kopparberg's wooden church, and Kopparberg Cider, now one of the best selling ciders in the UK and worldwide.