Guernica is a large 1937 oil painting by Spanish artist Pablo Picasso. It is one of his best-known works, regarded by many art critics as the most moving and powerful anti-war painting in history. It is exhibited in the Museo Reina Sofía in Madrid.

The grey, black, and white painting, on a canvas 3.49 meters (11 ft 5 in) tall and 7.76 meters (25 ft 6 in) across, portrays the suffering wrought by violence and chaos. Prominently featured in the composition are a gored horse, a bull, screaming women, a dead baby, a dismembered soldier, and flames.

Picasso painted Guernica at his home in Paris in response to the 26 April 1937 bombing of Guernica, a town in the Basque Country in northern Spain, by Nazi Germany and Fascist Italy. Upon completion, Guernica was exhibited at the Spanish pavilion at the 1937 Paris International Exposition and then at other venues around the world. The touring exhibition was used to raise funds for Spanish war relief. The painting soon became widely acclaimed, helping to bring worldwide attention to the Spanish Civil War that took place from 1936 to 1939.

It is widely thought that Surrealist photographer and anti-fascist activist Dora Maar, Picasso's romantic partner at the time, had a significant influence on the style and politicized theme of Guernica.

Pablo Diego José Francisco de Paula Juan Nepomuceno María de los Remedios Cipriano de la Santísima Trinidad Ruiz y Picasso (25 October 1881 – 8 April 1973) was a Spanish painter, sculptor, printmaker, ceramicist, and theatre designer who spent most of his adult life in France. One of the most influential artists of the 20th century, he is known for co-founding the Cubist movement, the invention of constructed sculpture, the co-invention of collage, and for the wide variety of styles that he helped develop and explore. Among his most famous works are the proto-Cubist Les Demoiselles d'Avignon (1907) and the anti-war painting Guernica (1937), a dramatic portrayal of the bombing of Guernica by German and Italian air forces during the Spanish Civil War.

Beginning his formal training under his father José Ruiz y Blasco aged seven, Picasso demonstrated extraordinary artistic talent from a young age, painting in a naturalistic manner through his childhood and adolescence. During the first decade of the 20th century, his style changed as he experimented with different theories, techniques, and ideas. After 1906, the Fauvist work of the older artist Henri Matisse motivated Picasso to explore more radical styles, beginning a fruitful rivalry between the two artists, who subsequently were often paired by critics as the leaders of modern art.

Picasso's output, especially in his early career, is often periodized. While the names of many of his later periods are debated, the most commonly accepted periods in his work are the Blue Period (1901–1904), the Rose Period (1904–1906), the African-influenced Period (1907–1909), Analytic Cubism (1909–1912), and Synthetic Cubism (1912–1919), also referred to as the Crystal period. Much of Picasso's work of the late 1910s and early 1920s is in a neoclassical style, and his work in the mid-1920s often has characteristics of Surrealism. His later work often combines elements of his earlier styles.