Harstad (help·info) is a municipality in Troms, Norway, most of which is located on the island of Hinnøya. With a population of 23,344, it is the second-most populated municipality in Troms. The municipal center of Harstad is the most populated town in Central Hålogaland and the third-largest in Northern Norway. The town was incorporated in 1904.

The municipality is located on two islands in south Troms. Most of the municipality is located on Hinnøya, which is Norway's largest coastal island (three islands in the Svalbard archipelago are larger). The northern part of the municipality is located on the southern half, 53 square kilometres (20 sq mi), of Grytøya. Harstad is bordered by the municipality of Bjarkøy to the north, Kvæfjord to the west, and Tjeldsund (in the county of Nordland) to the south. To the southeast the Tjeldsund Bridge connects Hinnøya with Skånland and the mainland across Tjeldsundet, and to the northeast is the Vågsfjorden, where Harstad shares a water border with Ibestad. The city itself is located northeast on Hinnøya; it is the only city on the island, and is popularly known as Vågsfjordens perle (The pearl of Vågsfjorden).