Harris is the southern and more mountainous part of Lewis and Harris, the largest island in the Outer Hebrides, Scotland. Although not an island itself, Harris is often referred to as the Isle of Harris, which is the former postal county and the current post town for Royal Mail postcodes starting HS3 or HS5.

The civil parish of Harris is considered to include St Kilda, an uninhabited archipelago 40 miles (65 kilometres) west-northwest of North Uist, and the uninhabited islet Rockall, which is 230 miles (370 kilometres) west of North Uist.

The boundary between Lewis and Harris is approximately a line from the head of Loch Resort on the west coast to the closest point of Loch Seaforth on the east coast. Harris itself divides naturally into northern and southern parts which are separated by West and East Loch Tarbert. These halves are joined by a narrow isthmus at the main settlement of Tarbert.

The bedrock of Harris is largely Lewisian gneisses, which were laid down in the Precambrian period, interspersed with igneous intrusions. One of these intrusions forms the summit plateau of the mountain Roinebhal. The rock here is anorthosite, and is similar in composition to rocks found in the mountains of the Moon.

Harris is a part of historic Inverness-shire, and was administered as such under older administrative divisions. In the 2001 census, Harris had a usually resident population of 1,916. It is part of the South Lewis, Harris and North Uist National Scenic Area, one of 40 in Scotland.