Estoril is a town in the Municipality of Cascais, Portugal, on the Portuguese Riviera. Estoril is famed as a luxury entertainment destination on the Portuguese Riviera, as home of the Casino Estoril. Estoril is one of the most expensive places to live in Portugal and the Iberian Peninsula. It is home to a sizable foreign expat community and known for its luxury restaurants, hotels, and entertainment. Cascais is consistently ranked for its high quality of living, making it one of the most livable places in Portugal.

Estoril is a major international tourist destination in Portugal, known for its luxury hotels, beaches, and the Casino Estoril. Famed for having been home of numerous royal families and famous personalities, Estoril is also known for the numerous notable events it hosts, such as the Estoril Open and the Lisbon & Estoril Film Festival.

The name comes from Old Portuguese estorga (Heather) - a common plant in the area - with the final meaning of "place where heather grows or is abundant". Alternatively, from Old Portuguese astor ( Northern goshawk ), meaning a place where such birds live.

The Museum of Portuguese Music - Casa Verdades de Faria hosts an important collection of musical instruments related to popular music, assembled by Michel Giacometti.

Christine McVie, from the band Fleetwood Mac, wrote a song called "Nights in Estoril" for their album Time.

Serbian-Portuguese author Dejan Tiago Stankovic published Estoril, a war novel in 2016, about Estoril during World War II.