Henderson Island is an uninhabited island in the south Pacific Ocean. It is part of the Pitcairn Island Group, together with Pitcairn, Oeno, and Ducie Islands. Measuring 9.6 by 5.1 kilometres, it has an area of 37.3 km2 (14.4 sq mi) and is located 193 km (104 nmi) northeast of Pitcairn Island, which is the only inhabited island of the group. It has poor soil and little fresh water, and is unsuitable for agriculture. There are three beaches on the northern end and the remaining coast comprises steep cliffs up to 15 m (50 ft) in height. In 1902, it was annexed to the Pitcairn Islands colony, which is now a British Overseas Territory.

The Pitcairn Islands, officially Pitcairn, Henderson, Ducie and Oeno Islands, are a group of four volcanic islands in the southern Pacific Ocean that form the sole British Overseas Territory in the Pacific Ocean. The four islands—Pitcairn, Henderson, Ducie and Oeno—are scattered across several hundred miles of ocean and have a combined land area of about 18 square miles (47 km2). Henderson Island accounts for 86% of the land area, but only Pitcairn Island is inhabited. The inhabited islands nearest to the Pitcairn Islands are Mangareva, 688 km to the west, as well as Easter Island, 1,929 km to the east.