Zenon Walter Pylyshyn FRSC (/ˈzɛnən pəˈlɪʃən/; 25 August 1937 – 6 December 2022) was a Canadian cognitive scientist and philosopher. He was a Canada Council Senior Fellow from 1963 to 1964.

Pylyshyn's research generally involved the theoretical analysis of the nature of the human cognitive systems behind perception, imagination, and reasoning. He developed visual indexing theory (sometimes called the FINST theory) which hypothesizes a pre-conceptual mechanism responsible for individuating, tracking, and directly (or demonstratively) referring to the visual objects that could be interrogated by cognitive processes. His very influential multiple object tracking experiment methodology emerged from this work.

Pylyshyn was born in Montreal, Quebec, Canada, to Ukrainian immigrants Anna and Yuriy. He obtained a degree in Engineering Physics (BEng 1959) from McGill University and in control systems (MSc 1960) and experimental psychology (PhD 1963), both from the Regina Campus, University of Saskatchewan.^{[citation needed]} His dissertation was on the application of information theory to studies of human short-term memory.^{[citation needed]}

Pylyshyn was a Canada Council Senior Fellow from 1963 to 1964.^{[citation needed]} He was then professor of Psychology and Computer Science, at the University of Western Ontario in London, from 1964 until 1994, where he also held honorary positions in Philosophy and Electrical Engineering and was director of the UWO Center for Cognitive Science. From 1985 to 1994, he directed the program in Artificial Intelligence and Robotics at the Canadian Institute for Advanced Research.

In 1994, he accepted positions as the Board of Governors Professor of Cognitive Science and as the director of the new Rutgers University Center for Cognitive Science in New Brunswick, New Jersey. In May 2016 Rutgers held a one-day "ZenFest", to commemorate his retirement.

Pylyshyn died, on 6 December 2022, at Calvary Hospital in New York City.