Larvik is a town and municipality in Vestfold in Vestfold og Telemark county, Norway. The administrative centre of the municipality is the city of Larvik. The municipality of Larvik has about 46,364 inhabitants.The municipality has a 110 km coastline, only shorter than that of neighbouring Sandefjord.

The city achieved market town status in 1671. Larvik was established as a municipality on 1 January 1838 (see formannskapsdistrikt). The city of Stavern, and the rural municipalities of Brunlanes, Hedrum, and Tjølling were forcefully merged into the municipality of Larvik on 1 January 1988. On 1 January 2018, neighboring Lardal was merged into Larvik as part of a nationwide municipal reform. After the merge, Larvik is the largest municipality in Vestfold by area, and the second-most populous municipality in the Vestfold district.

Larvik is known as the hometown of Thor Heyerdahl. It is also home to Bøkeskogen, the northernmost beech tree forest in the world. It is also home of Norway's only natural mineral water spring, Farriskilden. Farris Bad has been described as one of the best spas in Europe. It has the largest spa department in Scandinavia.

Larvik has a daily ferry connection to Hirtshals, Denmark.

Larvik is first and foremost known as a summer community. Due to its stable climate and one of Norway's highest median temperatures, Larvik experiences significant summer tourism. Larvik's climate is among the mildest in Norway, with one of the nation's highest number of annual sunshine days. It is home to over 4,000 holiday homes.

The coastal town of Stavern and picturesque villages of Helgeroa and Nevlunghavn receive large numbers of tourists during summer months. Stavern is known as a summer community, and its population more than doubles during summers. Tourist attractions in Stavern include Hall of Remembrance, Fredriksvern, and Citadellet. Citadel Island is home of Staverns Fortress which dates to the 1680s. The island is a current refuge for artists.

Kaupang has been described as the "chief attraction" for visitors in Larvik. Kapuang is also known as Norway's most important monument from the Viking Age. Another source describes Mølen Geopark as Larvik's most visited tourist attraction. Other attractions include the Maritime Museum, Fritzøehus, Herregården, the home of Thor Heyerdahl, and Bøkeskogen. Larvik is also home to Farris Bad, the largest spa in the Nordic countries, which has been described as one of Europe's best spa facilities.