Hans Peter Wilhelm Arp (/ɑːrp/; German: [aʁp]; 16 September 1886 – 7 June 1966), better known as Jean Arp in English, was a German-French sculptor, painter and poet. He was known as a Dadaist and an abstract artist.

Arp was born Hans Peter Wilhelm Arp to a French mother and a German father in Strasbourg during the period between the Franco-Prussian War and World War I, when the city and surrounding region were under the control of the German Empire. Following the return of Alsace to France at the end of World War I, French law required Arp to adopt a French name, and he legally became Jean Arp, although he continued referring to himself as "Hans" when he spoke German.

In 1904, after leaving the École des Arts et Métiers in Strasbourg, he went to Paris where he published his poetry for the first time. From 1905 to 1907, he studied at the Weimarer Kunstschule in Germany, where he met his uncle, German landscape painter Carl Arp. In 1908 he returned to Paris, where he attended the Académie Julian. Arp was a founder-member of the first modern art alliance in Switzerland Moderne Bund in Lucerne in 1911, participating in their exhibitions from 1911 to 1913.

In 1912 he went to Munich and called on Wassily Kandinsky, the influential Russian painter and art theorist. Arp was encouraged by him in his researches and exhibited with the Der Blaue Reiter group. Later that year, he took part in a major exhibition in Zürich, along with Henri Matisse, Robert Delaunay, and Kandinsky. In Berlin in 1913, he was taken up by Herwarth Walden, the dealer and magazine editor who was at that time one of the most powerful figures in the European avant-garde.

In 1915 he moved to Switzerland to take advantage of Swiss neutrality. Arp later told the story of how, when he was notified to report to the German consulate in Zürich, he pretended to be mentally ill in order to avoid being drafted into the German Army: after crossing himself whenever he saw a portrait of Paul von Hindenburg, Arp was given paperwork on which he was told to write his date of birth on the first blank line. Accordingly, he wrote "16/9/87"; he then wrote "16/9/87" on every other line as well, then drew one final line beneath them and, "without worrying too much about accuracy", calculated their sum. Hans Richter, describing this story, noted that "they [the German authorities] believed him."

It was at an exhibition that year where he first met the artist Sophie Taeuber who was to become his collaborator in the production of works of art and a significant influence on his artistic style and working method. They married on 20 October 1922.

In 1916 Hugo Ball opened the Cabaret Voltaire, which was to become the centre of Dada activities in Zürich for a group that included Arp, Marcel Janco, Tristan Tzara, and others. In 1920, as Hans Arp, along with Max Ernst and the social activist Alfred Grünwald, he set up the Cologne Dada group. In 1925 his work also appeared in the first exhibition of the Surrealist group at the Galérie Pierre in Paris.

In 1926 Arp moved to the Paris suburb of Meudon. In 1931 he broke with the Surrealist movement to found Abstraction-Création, working with the Paris-based group Abstraction-Création and the periodical, Transition. Beginning in the 1930s the artist expanded his efforts from collage, assemblage (Trousse d'un Da, 1921) and bas-relief to include bronze and stone sculptures. He produced several small works made of multiple elements that the viewer could pick up, separate, and rearrange into new configurations.