Ray Thorburn
(1937 - 2023)

Raymond Wallace Thorburn was a New Zealand artist, art educator and museum director.

https://en.wikipedia.org/wiki/Ray_Thorburn_(artist)

Modular 13, series 2
1970
acrylic on hardboard
101.4 × 101.4 cm 
Te Papa, Wellington, New Zealand
https://collections.tepapa.govt.nz/object/43822?page=1&rtp=1&ros=1&asr=1&assoc=all&mb=c

Victor Vasarely
(1906 - 1997)

Victor Vasarely was a Hungarian-French artist, who is widely accepted as a "grandfather" and leader of the Op art movement. 

https://en.wikipedia.org/wiki/Victor_Vasarely

DIA OR CF
1968
serigraphy
68 x 68 cm
Olomouc Museum of Art, Olomouc 9, Czechia

Marina Apollonio
(b. 1940)

Marina Apollonio is an Italian painter and optical artist. She lives and works in Padua.

In 1963, Apollonio produced her first work, Metal Reliefs with Alternate Color Sequences. She shared with other Op-Artists the interest in a depersonalized art, as opposite to Abstract Expressionism. She used industrial material in her process, creating dynamic and fluctuating environments in the user's perception.

https://en.wikipedia.org/wiki/Marina_Apollonio

Circular Dinamic 6S blue + red
1966
oil on canvas
40 x 40 cm
Private collection. Sold Friday 18 December 2020, 03:00 PM • Rome 
https://www.finarte.it/asta/arte-moderna-e-contemporanea-roma-2020-12-18/marina-apollonio-dinamica-circolare-6s-blu-rosso-58289?lang=en

Kazys Varnelis
(1917 - 2010)

Kazys Varnelis was an abstract painter from Lithuania. He lived and worked in the United States of America for fifty years, between 1949 and 1998. His distinctive painting style demonstrated optical and three-dimensional illusions based on geometric abstractions and minimal forms. His style combined elements of constructivism, minimalism, and op art. His work is sometimes described as a modernist interpretation of Lithuanian folk art and is owned by Solomon R. Guggenheim Museum, the Art Institute of Chicago, Currier Museum of Art, and other museums.

https://en.wikipedia.org/wiki/Kazys_Varnelis_(artist)

Synchrony
1969
Acrylic on Canvas
198,1cm x 149,2 cm
Lithuanian Art Centre TARTLE, Vilnius, Lithuania

Julian Stanczak
(1928 - 2017 )

Julian Stanczak was a Polish-born American painter and printmaker who is considered a central figure of the Op art movement in the U.S. during the 1960s and 1970s. Described as an artist whose work "evinced a tremendous geometric inventiveness", Stanczak is primarily known for his large-scale polychromatic abstract compositions made using acrylic paint on canvas in which he explored the perceptual dimensions of color.

https://en.wikipedia.org/wiki/Julian_Stanczak

And Then There Were Three
1971
acrylic on canvas
121.9 x 365.8cm
Toledo Museum of Art, Toledo, Ohio, USA
https://emuseum.toledomuseum.org/objects/58734/and-then-there-were-three

 Jesús Rafael Soto
(1923–2005)

Jesús Rafael Soto was a Venezuelan kinetic and op artist, a sculptor and a painter.

https://en.wikipedia.org/wiki/Jesús_Rafael_Soto

Sin título
Serigraphy
60 x 60 cm
Inter-American Development Bank, Washington, United States

<b>Horacio Garcia Rossi</b> 
 (1929–2012)

<i>Horacio Garcia Rossi was an Argentine painter and kinetic artist. In 1960, he was one of the co-founders of the group of artists Groupe de Recherche d’Art Visuel (GRAV), alongside Julio Le Parc, François Morellet, Francisco Sobrino, Joël Stein and Yvaral.</I>

https://fr.wikipedia.org/wiki/Horacio_Garcia_Rossi

Composition in green
1978
Acrylic on canvas
26 x 26 cm
Private collection (sold on 30 October 2023)
https://www.arsvalue.com/en/lots/908892/horacio-garcia-rossi-1920-2012-composition-verte-1978-acrilico-su