Campbell Island is an uninhabited subantarctic island of New Zealand, and the main island of the Campbell Island group. It is surrounded by numerous stacks, rocks and islets like Dent Island, Folly Island (or Folly Islands), Isle de Jeanette-Marie, and Jacquemart Island, the latter being the southernmost extremity of New Zealand. The Island is mountainous, rising to over 500 metres in the south. A long fjord, Perseverance Harbour, nearly bisects it, opening out to sea on the east coast.

Campbell Island was discovered in 1810 by Captain Frederick Hasselborough of the sealing brig Perseverance, which was owned by shipowner Robert Campbell's Sydney-based company Campbell & Co. (whence the island's name). Captain Hasselborough was drowned on 4 November 1810 in Perseverance Harbour.

The island became a seal hunting base, and the seal population was almost totally eradicated. The first sealing boom was over by the mid-teens of the 19th century. The second was a brief revival in the 1820s. The whaling boom extended here in the 1830s and ’40s. In the late 19th century, the island became a pastoral lease. Sheep farming was undertaken from 1896 until the lease, with the sheep and a small herd of cattle, was abandoned in 1931 as a casualty of the Great Depression.

During World War II, a coastwatching station was operative at Tucker Cove at the north shore of Perseverance Harbour as part of the Cape Expedition program. After the war, the facilities were used as a meteorological station until 1958, when a new one was established at Beeman Cove, just a few hundred metres further east.

The island is part of the Campbell Island group Important Bird Area (IBA), identified as such by BirdLife International because of its significance as a breeding site for several species of seabirds as well as the endemic Campbell Teal and Campbell Snipe.

In 1954, the island was gazetted as a nature reserve. The area is one of five subantarctic island groups designated as a World Heritage Site by UNESCO.