Opened in 2019 in the renovated White Granary building, the 250-piece collection of portraits by Stanisław Ignacy Witkiewicz (1885–1939), aka Witkacy, are the unrivalled highlight of Słupsk's museum. Witkacy was a controversial writer, photographer and painter who specialised in weird-and-wonderful portraits that he produced in a drugged state at his 'portrait company'. Słupsk has no connection to the artist – the museum bought 110 of the pastels from the son of Witkacy's doctor and friend from Zakopane in the 1960s.
Some 40 more were added in the 1970s, this time coming mainly from the artist's dentist. Around 125 are displayed at any one time and the exhibition is changed every few months. The body of work is fascinating, Witkacy having captured the essence of his subjects, sometimes to grotesque effect.