The Wessel Islands is a group of uninhabited islands in the Northern Territory of Australia. They extend in a more or less straight line from Buckingham Bay and the Napier Peninsula of Arnhem Land, and Elcho Island, to the northeast. Marchinbar Island is the largest of the group. Other islands include Elcho Island, Rimbija Island (the most outlying island), Guluwuru, Raragala, Stevens Island, Burgunngura, Djeergaree, Yargara, Drysdale Island, Jirrgari Island, Graham Island, Alger Island, Abbott Island, and Howard Island.

Bumaga Island and Warnawi Island, both part of the Wessel Islands group, are also part of the Cunningham Islands.

The Wessel Islands constituted the homelands of the Nango or Yan-nhaŋu.

The islands were mapped and named by a Dutch expedition that sailed from Banda Neira to explore the coasts of New Guinea and the South Land following up on discoveries made in 1623 by Jan Carstensz and Willem van Colster (who named Arnhem Land after his ship Arnhem). The expedition used two small yachts that had been prefabricated in the Netherlands and were assembled on the Banda Islands, the Cleen Amsterdam and the Wesel.

The ships sailed on 17 April 1636 under the command of Gerrit Thomas Pool, who was killed on New Guinea just 11 days later. The merchant Pieter Pieterszoon took over command and continued the voyage, returning to Banda. Besides the Wesel Eilanden, named after the ship, Pietersen described the Cobourg Peninsula, Melville Island (Roode hoek), and Dundas Strait (which he misidentified as a bay). 170 years later Matthew Flinders decided to retain the name of the islands, though he slightly modified it to Wessel. The cities of Arnhem and Wesel, ultimate sources of the names of Arnhem Land and Wessel Islands, are themselves only 60 km (37 miles) separated.

Much of the population of the Wessel Islands was decimated by smallpox. It may have been introduced from Makassar by Makassan traders during the 1790s, though there is also evidence that smallpox spread from Sydney Cove, after 'variolous matter' was brought there in 1788 by the First Fleet. This dried matter from smallpox scabs was used in a technique called variolation, which was used as protection against the disease prior to the development of vaccination. By the early nineteenth century, many of the Yolngu clans had been wiped out.

During World War II, a string of observational outposts were set up along the Wessel Islands. A minesweeper, the Patricia Cam, was sunk by a Japanese float plane on 22 January 1943. A Yolngu account of the incident, and attempts to save the survivors was taken down from one of the latter, Narritjin Maymuru.

Since the 1960s, the islands have had no permanent settlements.