1866 births

James Ramsay MacDonald (né James McDonald Ramsay; 12 October 1866 – 9 November 1937) was a British statesman and politician who served as Prime Minister of the United Kingdom, the first who belonged to the Labour Party, leading minority Labour governments for nine months in 1924 and again between 1929 and 1931. From 1931 to 1935, he headed a National Government dominated by the Conservative Party and supported by only a few Labour members. MacDonald was expelled from the Labour Party as a result.
MacDonald, along with Keir Hardie and Arthur Henderson, was one of the three principal founders of the Labour Party in 1900. He was chairman of the Labour MPs before 1914 and, after an eclipse in his career caused by his opposition to the First World War, he was Leader of the Labour Party from 1922. The second Labour Government (1929–1931) was dominated by the Great Depression. He formed the National Government to carry out spending cuts to defend the gold standard, but it had to be abandoned after the Invergordon Mutiny, and he called a general election in 1931 seeking a "doctor's mandate" to fix the economy.
The National coalition won an overwhelming landslide and the Labour Party was reduced to a rump of around 50 seats in the House of Commons. His health deteriorated and he stood down as Prime Minister in 1935, remaining as Lord President of the Council until retiring in 1937. He died later that year.
MacDonald's speeches, pamphlets and books made him an important theoretician. Historian John Shepherd states that "MacDonald's natural gifts of an imposing presence, handsome features and a persuasive oratory delivered with an arresting Highlands accent made him the iconic Labour leader". After 1931, MacDonald was repeatedly and bitterly denounced by the Labour movement as a traitor to its cause. Since the 1960s, some historians have defended his reputation, emphasising his earlier role in building up the Labour Party, dealing with the Great Depression, and as a forerunner of the political realignments of the 1990s and 2000s.

Saint Marie-Adolphine Dierkx (1866–1900, born Anna Catharina or Kaatje Dierkx) was a Dutch nun who died for her faith in China during the Boxer Rebellion and was canonised in 2000. She is one of the group known as the Martyr Saints of China who were canonised by Pope John Paul II on 1 October 2000. Her birthplace has been converted into a chapel.

Saint Marie-Hermine of Jesus (1866–1900, born Irma Grivot) was a French nun and Mother Superior who died during the Boxer Rebellion in China and was canonised in 2000. She and six other nuns had gone to China to create a small hospital and to staff an orphanage, but were ultimately killed due to their association with foreign interference. She is one of the group known as the Martyr Saints of China who were canonised by Pope John Paul II 1 October 2000.

Henri Joly (1866–1945) was a French inventor and businessman. He developed early versions of motion picture film, cameras, and projectors.

Gustave Cabaret (1 November 1866 – 4 April 1918) was a French archer. He competed at the 1908 Summer Olympics in London. Cabaret entered the men's double York round event in 1908, taking 26th place with 191 points. That last-place finish was not repeated in the second event of the men's archery competitions in 1908. Cabaret won the bronze medal in the Continental style, scoring 255 points to finish 8 behind Eugène Grisot and only 1 behind Louis Vernet.

Gilbert or Émile Bougnol (31 August 1866 in Saint-Myon, France – 20 October 1947 in Rueil-Malmaison, France) was a French professional fencer who competed in the late 19th century and early 20th century. He participated in Fencing at the 1900 Summer Olympics in Paris and won the silver medal in the masters épée.

Émile Auguste Joseph De Wildeman (19 October 1866, Saint-Josse-ten-Noode – 1947) was a Belgian botanist and phycologist. He is known for his investigations of Congolese flora.
From 1883 to 1887, he studied pharmacy at the Université libre de Bruxelles. In 1891, he began work as a preparateur at the Botanical Garden of Brussels, an institution where he later served as director. In 1892, he received his doctorate in sciences (academic advisor, Leo Errera) and in 1926 attained the title of professor.

Charles-Jean Étienne Gustave Nicolas, baron de la Vallée Poussin (French pronunciation: [ʃaʁl ʒɑ̃ etjɛn ɡystav nikɔla baʁɔ̃ də la vale pusɛ̃]; 14 August 1866 – 2 March 1962) was a Belgian mathematician. He is best known for proving the prime number theorem.
The King of Belgium ennobled him with the title of baron.

Frédéric Jean Edmond Swarts (2 September 1866 – 6 September 1940) was a Belgian chemist who prepared the first chlorofluorocarbon, CF2Cl2 (Freon-12) as well as several other related compounds. He was a professor in the civil engineering at the University of Ghent. In addition to his work on organofluorine chemistry, he authored the textbook "Cours de Chimie Organique." He was a son of Theodore Swarts (chemist, *1839 Antwerpen; †1911 Kortenberg, Belgium) and a colleague of Leo Baekeland.

Marin Molliard (8 June 1866, in Châtillon-Coligny – 24 July 1944, in Paris) was a French botanist.
From 1888 he studied at the École Normale Supérieure in Paris, where he successively earned degrees in mathematics (1889), physics (1890) and natural sciences (1891). In 1892 he obtained his agrégation, and two years later became chef de travaux to the faculty of sciences at Paris. In 1922 he became a lecturer at the École Normale supérieure de Saint-Cloud, and from 1923 to 1936 served as director of the laboratory of plant biology in Avon. In 1937 he received the title of honorary professor.In 1923 he was named president of the Société botanique de France. During the same year he was elected as a member of the Académie des sciences (section of botany).In 1904 he was the first to describe conidia in the fungal genus Sarcoscypha. In 1984 John W. Paden introduced the generic name Molliardiomyces for the anamorphic states of Sarcoscypha and the related genus Phillipsia.