Frostisen is a glacier on the border of the municipalities of Ballangen and Narvik in Nordland county, Norway. It is one of the larger plateau glaciers in Norway. Frostisen covers an area of about 25 square kilometres (9.7 sq mi). The elevation of the glacier ranges from 840 to 1,710 metres (2,760 to 5,610 ft) above sea level. The glacier lies near the Skjomen fjord, a branch of the Ofotfjord, just southwest of the city Narvik.