Orsa is a locality and the seat of Orsa Municipality, Dalarna County, Sweden, with 5,308 inhabitants (2010). It is located in the northern part of lake Siljan, about 15 kilometres (9 miles) north of the town Mora. Inlandsbanan and European route E45 run through the town and the railroad Bollnäs-Orsa connects.
The southern parts of Orsa are characterized by the Siljan Ring, the ring of lakes and rivers in northern Dalarna formed by the big meteorite strike 365 million years ago. In central Orsa, at the ouflow of river Oreälven a sand bank has been built up, in these days enjoyed by thousands of visitors and the inhabitants of Orsa. The big forests start just north of the town of Orsa, with the sparsely populated Orsa finnmark, to which many Finns emigrated during the 17th century.
Orsa is a genus of moths of the Noctuidae family.
Orsa or ORSA may refer to: