Finistère (/ˌfɪnɪˈstɛər/; French: [finistɛʁ] ^ⓘ; Breton: Penn-ar-Bed [ˌpɛnarˈbeːt]) is a department of France in the extreme west of Brittany. Its prefecture is Quimper and its largest city is Brest. In 2019, it had a population of 915,090.

The present department consists of the historical region of Léon and parts of Cornouaille and Trégor, both parts of pre-revolutionary Brittany.

The name Finistère derives from the Latin Finis Terræ, meaning end of the earth. In England, a similar area is called Land's End. The Breton name for Finistère, Penn ar Bed, translates as "Head/End of the World" and is similar to the Cornish name for Land's End, Pedn an Wlas (Head/End of the country), and also Penfro (English: Pembroke) in Wales (pen = end, bro = country). Finistère is not to be confused with Fisterra in Galicia, Spain, which shares the same etymology.

The area of the department was part of the Province of Brittany before 1790.

The largest population centre in Finistère is Brest. Other large towns in the department include Quimper (the capital), Concarneau, Morlaix, Carhaix, Quimperlé and Douarnenez. Finistère includes the island of Ushant (Eusa in Breton, Ouessant in French).

Finistère is the westernmost department of Metropolitan France and can also claim to be the "most coastal" department in Metropolitan France. Of its 277 communes, 117 are located on the coast (approximately 42% of the total number of communes). Its total coastline of approximately 1,250 km (776.71 mi) accounts for almost a quarter of the entire Brittany coast-line.

The abers, rugged fjord-like inlets on the north coast, are a notable feature of the landscape.

The westernmost point of continental France, known as the Pointe de Corsen, extends from the northwestern tip of Finistère. About 40 kilometres to the south (as the crow flies) is the slightly less westerly, but rugged and isolated, headland of Pointe du Raz.