Gonzalo Fonseca (2 July 1922 – 11 June 1997) was a Uruguayan artist known for his stone sculpting. He originally studied to be an architect at the University of Montevideo, but discovered modern art in 1942 after working in the Taller Torres-Garcia workshop. He studied painting in the workshop until 1949, and became interested in pre-Columbian art during that time. Fonseca is frequently associated with the movement Universal Constructivism.

Fonseca was born in Montevideo, Uruguay, in July 1922. He traveled to Europe in the 1930s, and was exposed to archaeology, anthropology, and history. Fonseca also taught himself to sculpt in stone and paint with watercolor. In 1939, he began studying architecture at the University of Montevideo. However, in 1942 Fonseca left the University to work with Joaquín Torres-García. While working at the Torres-Garcia workshop, he became more diverse in his techniques, trying sculpting, painting, ceramics, and drawing. During the course of the 1940s, Fonseca traveled through Peru and Bolivia, studying art with other members of the Torres-Garcia workshop.

In 1950 he left Uruguay, and traveled through several countries in Europe and the Middle East. Fonseca worked in excavations run by Flinders Petrie in Egypt, Sudan, Syria, and traveled through Lebanon, Jordan, Turkey, and Greece. These archeological digs would prove fundamental in his future artworks. While living in Europe, he worked in ceramics as well as painting.

He met and married Elizabeth Kaplan, from New York City, in the mid-1950s (and divorced two decades later) and moved to Manhattan in 1958 after being awarded a Simon Guggenheim Fellowship. He had four children, Quina, Bruno, Caio, and Isabel with Elizabeth Kaplan, two of whom (Bruno Fonseca and Caio Fonseca) became renowned artists. Their youngest child Isabel Fonseca became a writer.

In 1962 Fonseca had his first exhibition in the United States, at the Portland Art Museum in Oregon. This exhibition contained mostly flat compositions, as was common with the works done by the Torres-Garcia workshop at that time. Fonseca also created wooden reliefs for this exhibition, which laid a foundation for his three-dimensional art. He began working in New York and in Italy, near Carrara. It is in the 1970s that he focuses on painting towards sculpture and on three-dimensional architectural forms. He started working on large scale pieces mostly of marble, and recycled limestone from New York's demolished buildings. In 1983, he became a citizen of the United States. During the late 1970s and 1980s he became more focused on towers, such as Torre del recien nacido ("Tower of the Newborn Child") and Torre de los vientos. He had few solo shows throughout his career, but several group exhibitions in which he became known for his stone sculptures of modern influenced architectural forms. He died in Italy at the age of 74 in Seravezza, Italy, in his studio.

As a Universal Constructivist, Fonseca sought to focus on art outside of nationality. This is clear in the amount of traveling and excavating he did, not trying to define a national identity but rather a universal identity, free of false stereotypes.

Fonseca's influence on his art derived from a fascination with history and cultures, and his early training as an architect helped him realize and formulate his sculptures. His pieces offer a sense of mystery, and yet a deeper meaning.

Fonseca's sculptures take architectural reference as well as that of ancient ruins and what he studied while taking part in excavations. This causes the viewer to recognize and identify parts of the sculpture, perhaps relating them to the characteristics of a building or home. But the way in which he manifests these pieces still leaves something to be defined by the viewer in relation to time and space. His works do not automatically construct a definite time period in the viewer's mind, leaving it to the imagination as to what it may or may not represent in time and space.