Ralph Douglas Vladimir Slocombe OBE, BSC, ASC, GBCT (10 February 1913 – 22 February 2016) was a British cinematographer, particularly known for his work at Ealing Studios in the 1940s and 1950s, as well as the first three Indiana Jones films. He won BAFTA Awards in 1964, 1975, and 1979, and was nominated for the Academy Award for Best Cinematography on three occasions.

Slocombe was born in Putney, London, the son of Marie (née Karlinsky) and journalist George Slocombe (1894–1963). His mother was Russian. His father was the Paris correspondent for the Daily Herald, and so Slocombe spent part of his upbringing in France, returning to the United Kingdom around 1933. He graduated with a degree in Mathematics from the Sorbonne.

Slocombe initially intended to become a photojournalist, and as a young photographer, he witnessed the early events leading up to the outbreak of World War II. Visiting Danzig in 1939, he photographed the growing anti-Jewish sentiment. In consequence, he was commissioned by American film-maker Herbert Kline to film events for a documentary called Lights Out, covering a Goebbels rally and the burning of a synagogue, for which he was briefly arrested. Slocombe was in Warsaw with a movie camera on 1 September 1939 when Germany invaded. Accompanied by Kline, he escaped, but his train was machine-gunned by a German aeroplane. In 2014, he said of the experience that:

I had no understanding of the concept of blitzkrieg. I had been expecting trouble but I thought it would be in trenches, like WW1. The Germans were coming over the border at a great pace ... We were trundling through the countryside at night. We kept stopping for no apparent reason, but we came to a screeching halt because a German plane was bombing us. After its first pass we climbed out the window and crawled under the carriage. The plane came back and started machine-gunning. A young girl died in front of us.

After escaping from the train, Slocombe and Kline bought a horse and cart from a Polish farm, finally returning to London via Latvia and Stockholm.

After returning to England, Slocombe became a cinematographer for the British Ministry of Information, shooting footage of Atlantic convoys with the Fleet Air Arm. He also developed a relationship with Ealing Studios, where filmmaker Alberto Cavalcanti, who helped him obtain his position, worked. Some of his photography was used as second unit material for fiction films.

Slocombe moved into photographing for feature films at Ealing Studios during the later 1940s, after being hired on the strength of his documentary work. Slocombe later described his early work on Champagne Charlie (1944) as amateurish, in one case resulting in a sequence having to be reshot. However, in his career, Slocombe worked on 84 feature films over a period of 47 years.

Slocombe would later speak approvingly of Ealing's culture of script development. However, he also noted that its restrictive studio system headed by Michael Balcon, in which outside work was not normally permitted, made it impractical for him to attempt to begin a career as a director, something which he had considered.