Ștefan Bertalan (*1930, Răcăştia, ✝2014, Timișoara, Romania) was one of the most significant figures of the Romanian neo-avant-garde. His art focused on research and process, with nature as its central theme. In 1965 he cofounded Groupe 111 with Roman Cotoșman and Constantin Flondor. This is considered to be the first experimental art collective in communist Romania. Later he was part of the interdisciplinary group Sigma (1969–1980). He studied natural forms with methodical, almost scientific curiosity, examining their structures, patterns, and basic logic. His work forms a mysterious microcosm where curiosity, philosophy, mathematics, cybernetics, and spirituality converge. His interest in natural processes led him to a cosmology in which man and nature are inseparable.