Frostisen

 or is a glacier in Narvik Municipality in Nordland county, Norway. It is one of the larger plateau glaciers in Norway. Frostisen covers an area of about . The elevation of the glacier ranges from above sea level. The glacier lies near the Skjomen fjord, a branch of the Ofotfjorden, just southwest of the town of Narvik. The village of Elvegård lies about east of the glacier. The lakes Geitvatnet, Isvatnet, Kjelvatnet, Nordre Bukkevatnet and Søre Bukkevatnet all lie just to the southwest of the glacier.