Neste Oyj (international name: Neste Corporation; former names Neste Oil Corporation and Fortum Oil and Gas Oy; Finnish pronunciation: [ˈneste]) is an oil refining and marketing company located in Espoo, Finland. It produces, refines and markets oil products, provides engineering services, and licenses production technologies. Neste has operations in 14 countries.

Neste shares are listed on the Nasdaq Helsinki. As of 2022, the Prime Minister's Office of Finland is the largest shareholder in the company, owning 35.91% of shares.

In 2021, Neste was the third largest company in Finland in terms of revenue.

The name "Neste" means "liquid" in Finnish.

Neste was founded in 1948 as the State petrol company of Finland with the purpose to ensure the availability of refined fuels in Finland. The company's headquarters was established in Espoo.

In 1955, Uolevi Raade became the company's CEO. In 1957, the first oil refinery in Finland was built at Naantali using US technology. The Porvoo refinery was built in 1965 in Sköldvik (Kilpilahti). Originally, much of the oil refined was of Soviet origin, though North Sea oil was used after the collapse of the USSR.

In 1971, Neste acquired half of Kesko-owned Kesoil.

Because of the operations of Neste, the oil crisis of 1973 had little effect in Finland.