On 25 May 2017, Sotheby’s London will offer at auction a selection of paintings, sculpture, furniture, prints and jewellery formerly in the collection of Alexander Iolas, the twentieth-century art dealer whose legacy is credited with defining the careers of the leading artists he championed. From mounting Andy Warhol’s first and last gallery exhibitions and introducing an American audience to Surrealism, to shaping the careers and movements of those with whom he forged personal and lasting friendships, Iolas played a vital role in the post-war art world. Over 150 lots will be offered for sale, with estimates ranging from £100 to £150,000.

During his 35-year career as a dealer, between 1945 and 1980, Iolas nurtured connections among artists, gallerists and collectors through his international network of galleries in New York, Paris, Milan, Geneva and Madrid. Unfairly overlooked in the roster of influential twentieth-century art dealers, including Ileana Sonnabend and Leo Castelli, in recent years Iolas has been hailed as the “proto-Gagosian” of his day at the dawn of the era of the mega gallery and the celebrity artist.

Georgina Gold, Senior Director, Sotheby’s Impressionist & Modern Art Department, London: “In many ways, Alexander Iolas lived a surreal life, and in constantly looking to the future and to the past, he was a Janus-like figure whose imprint on art history should not be underestimated.”

Iolas had a talent for friendship, maintaining close relationships with some of the most prominent cultural figures of the time. His devotion to artists was unwavering: he not only extended the hand of friendship and financial support, he also played an important role in the creation of their artistic output, inspiring ideas and themes. From de Chirico, he commissioned costumes and set designs for a ballet production in Athens; in the mid-1980s he proposed to Warhol that the artist create a series of works based on Leonardo da Vinci’s ‘The Last Supper’ for an exhibition in Milan, a project Warhol relished. The bond between Warhol and Iolas was especially strong, and the two continued to work together closely until their deaths, only months apart in 1987.

Iolas staged pivotal exhibitions of new work by Max Ernst and René Magritte, fostered the talents of artists such as Lucio Fontana and Claude Lalanne, and also connected with the Pop sensibility of Ed Ruscha and the eroticism of Takis, giving shows to both. He was even one of the few people at the time to fully embrace Picasso’s late paintings, when these works by the artist were undervalued and unappreciated by all but a discerning few.

When Iolas died, the New York Times noted that he would be remembered as a dealer who could convince a client with “his hierophantic manner, his often sensational mode of dress and his mischievous and sometimes irresistible charm.” He cut a swathe through the art world with his flamboyant persona, and a legend formed that was in part of his own making. Extraordinary stories – possibly apocryphal – swirled around him: it was said that he had married Theodora Roosevelt to attain a Green Card and that curls of his hair were made into false eyelashes for Marlene Dietrich.