István Nádler (1938, Visegrad) is a Hungarian painter, graphic artist and sculptor.

Nádler studied at the Hungarian Academy of Fine Arts. At the time, he was a member of the Zugloi Kör group (until 1968). His works at the time were inspired by Kandinsky, Klee, and Malevich, and followed the tradition of French lyrical abstraction. Following his graduation in 1964, he went on a study trip across Europe, offered to him by the Károly Foundation.

He was a participant of the Ipartev exhibitions and a member of the Budapesti műhely group (including János Fajó, Ilona Keserü, Sándor Molnár, and Imre Bak) – one of the most notable phenomena in Hungarian Neo-Avant-garde art.

His works follow Hungarian constructivist tradition and lean towards geometrization. His use of colour includes high contrasts and full areas of colour. In the 1970s, his works are comparable to minimalism, using shades of grey and straight lines. In the 1980s, his style became more influenced by calligraphic motifs and ease of brushwork. Nádler's work process is inspired by music, particularly compositions by Steve Reich, László Vidovszky, Péter Eötvöse, and László Sáry. In the late 1980s, he returned more to the use of colour and embraced postmodernism.