Lenvik (Leaŋgáviika) is a former municipality that was located in the old Troms county, Norway. The municipality existed from 1838 until its dissolution in 2020. The municipality was partly situated on the mainland and partly on the island of Senja in what is now Senja Municipality in Troms og Finnmark county. The administrative centre was the town of Finnsnes, where the Gisund Bridge connects Senja to the mainland on Norwegian County Road 86. Other villages in the municipality included Aglapsvik, Gibostad, Botnhamn, Fjordgård, Finnfjordbotn, Husøy, Langnes, Laukhella, Silsand, and Rossfjordstraumen. The lake Lysvatnet was located in the municipality on Senja island, west of Gibostad.
At the time of its dissolution as a municipality on 1 January 2020, the municipality was the 126th largest by area out of the 422 municipalities in Norway. Lenvik was also the 101st most populous municipality in Norway with a population of 11,644. The municipality's population density was and its population has increased by 4.3% over the previous decade.
The large municipality of Lenvik was established on 1 January 1838 (see formannskapsdistrikt). In 1848, most of the mainland parts of Lenvik (population: 2,616) was separated to form the new Målselv Municipality, leaving Lenvik with 3,029 residents. Then in 1855, the northern part of Lenvik (population: 811) was separated to form the new municipality of Hillesøy. This left Lenvik with 2,757 inhabitants. On 1 January 1871, a small part of Lenvik (population: 70) was transferred to the neighboring municipality of Malangen.
During the 1960s, there were many municipal mergers across Norway due to the work of the Schei Committee. On 1 January 1964, many several neighboring areas were merged into Lenvik:
the part of Sørreisa Municipality on the island of Senja (population: 129)
the Hellemo, Paulsrud, Johnsgård, and Stormo farms in Tranøy Municipality (population: 106)
the part of Hillesøy Municipality on the island of Senja and the whole island of Hekkingen (population: 1,159)
These areas joined to old areas of Lenvik to form a new, larger municipality of Lenvik with a total population of 10,219.