Bridget Riley (b. 1931) is an English painter known for her singular op art paintings whose abstract compositions yield a sense of visual pleasure for the viewer, a notion derived as much from the artist's formative encounters with Old Master and Impressionist painting as from her early experiences with nature.

Riley began her career painting figurative subjects in a semi-impressionist manner, then changed to pointillism around 1958, mainly producing landscapes. In 1960 she evolved a style in which she explored the dynamic potentialities of optical phenomena, focusing exclusively on seemingly simple geometric forms, such as lines, circles, curves, and squares, arrayed across a surface - whether a canvas, a wall, or paper - according to an internal logic. These so-called 'Op-art' pieces, such as Fall (1963), produce a disorienting physical effect on the eye and actively engage the viewer, at times triggering sensations of vibration and movement. This sense of dynamism was explored to great effect in the artist's earliest black-and-white paintings, which established the basis of her enduring formal vocabulary. In 1967, Riley introduced colour into her work, thus expanding the perceptual and optical possibilities of her compositions.