Donald Judd (1928-1994) was one of the originators of Minimal Art, which it came into being in the 1960s.
Minimal Art reacted against the symbolism, spontaneity, and emotional intensity of Abstract Impressionism. Rather than expression, Minimal Art artists sought after objectivity. By removing 'distractions' like composition, theme, representation and so on, they wanted to allow the viewer to experience the work as a whole, and in its own respect.
Judd's work is highly geometrical, and many of his works are arrangements of repeated, freestanding objects. Judd used humble and honest materials such as metals, industrial plywood, concrete and color-impregnated plexiglas. His works tends to constrast with their environment, creating an interesting tension.
Overall, Judd has led the way for many of his peers, and minimalism as such.