Halmahera (also known as Jailolo or Gilolo) is the largest island in the Maluku Islands. It is part of the North Maluku province of Indonesia and Sofifi, the capital of the province, is located on the west coast of the island.

Halmahera has a land area of 17,780 km² (6,865 sq mi) and a population in 1995 of 162,728. Approximately half of the island's inhabitants are Muslim and half are Christian.

Sparsely-populated Halmahera's fortunes have long been closely tied to those of the smaller islands of Ternate and Tidore, both off its west coast. These islands were both the sites of major kingdoms in the era before Dutch East India Company colonized the entire archipelago.

During World War II, Halmahera was the site of a Japanese naval base at Kao Bay.

In 1999 and 2000 Halmahera was the site of violence that began as a purely ethnic dispute between residents of (mainly Christian) Kao and (entirely Muslim) Malifut sub-districts and then took on a religious nature as it spread through much of the North Moluccas (see: Maluku sectarian conflict). Thousands of people on Halmahera were killed in the fighting between religious militias. In June 2000, about five hundred people were killed when a ferry carrying refugees from the fighting on Halmahera sank off the northeast tip of Sulawesi island. Conspiracy theories about this event abound. A memorial to this tragedy can be found in Duma village in North Halmahera district.