Tomato Cain and Other Stories by Nigel Kneale (1949) — Kneale grew up on the island and this collection of short stories draws directly on Manx life: remote villages, superstition woven into daily routine, and an island community that feels simultaneously connected and cut off from the wider world. It won the Somerset Maugham Award in 1950. Kneale went on to write the BBC's Quatermass serials, but this early work remains his most rooted in the island.
English Passengers by Matthew Kneale (2000) — Nigel Kneale's son writes from multiple perspectives, including a crew of Manx sailors in the mid-19th century, to tell a story about a Victorian expedition to Tasmania. The Manx sections are vivid and the novel won the Whitbread Book of the Year.
The Book of Man by Fenella Bazin — A collection of Manx folk tales and legends, covering the island's supernatural traditions including the Moddey Dhoo (the Black Dog of Peel Castle), the buggane, and the little people of Manx folklore.
For historical background, the Manx National Heritage website and visitor centres are excellent resources, particularly on the island's Norse and Celtic heritage.