Walter Conrad Arensberg (April 4, 1878 – January 29, 1954) was an American art collector, critic and poet. His father was part owner and president of a crucible steel company. He majored in English and philosophy at Harvard University. With his wife Louise (born as Mary Louise Stevens, 1879–1953), he collected art and supported artistic endeavors.
Walter Arensberg was born in Pittsburgh, Pennsylvania, the oldest child of Conrad Christian Arensberg and his second wife, Flora Belle Covert. Walter's father was President and partial owner of a successful Pittsburgh crucible company. Between 1896 and 1900, Walter attended Harvard University. Following graduation, he travelled to Europe, where he spent at least two years. In 1903, he returned to Harvard, as a graduate student. He did not complete his degree, but rather moved to New York City to work as a cub reporter from 1904-1906.
Arensberg's work The cryptography of Shakespeare (1922) claims to find acrostics and anagrams in the published works of Shakespeare which reveal the name of Bacon. In The secret grave of Francis Bacon and his mother in the Lichfield chapter house (1923) and The Shakespearean mystery (1928) he used a "key cipher" to find further messages connected with the Rosicrucians. Analysis by William Friedman and Elizebeth Friedman shows that none of the methods has cryptographic validity.
Several volumes of his Symbolist-influenced verse were also published, including 1914's Poems and 1916's Idols. His poem Voyage a l'Infini was anthologized by Edmund Clarence Stedman.
Between 1913 and 1950 the couple collected the works of Modern artists such as Jean Metzinger,Marcel Duchamp,Charles Sheeler, Walter Pach, Beatrice Wood, and Elmer Ernest Southard, as well as Pre-Columbian art; they were assisted by dealer Earl L. Stendahl. The Arensbergs became particularly close with Duchamp, who lived in their apartment during the summer of 1915 while they vacationed at their summer home in Pomfret, Connecticut. They would become the artist's lifelong patrons and form the largest, most significant collection of his work. When Duchamp's idea to despatch his urinal to the first show of the Society of Independent Artists was rejected, both he and Arensberg felt obliged to resign from the society.