Lucio Costa (February 27, 1902, Toulon, France - June 13, 1998, Rio de Janeiro) was a Brazilian architect and urban planner.

Educated in England and Montreaux until 1916, he graduated as an architect in 1924 from the School of Fine Art (Escola Nacional de Belas Artes) in Rio de Janeiro. In 1930 Costa established a partnership with Russian architect Gregori Warchavchik , and became the Manager of the School of Fine Art.

Costa became a figure associated with reconciling traditional Brazilian forms and construction techniques with international modernism, particularly the work of Le Corbusier. With the Brazilian pavilion at the New York World's Fair of 1939 (designed with Oscar Niemeyer), with the Parque Guinle residential complex in Rio of 1948, and with the Hotel do Park São Clemente in Nova Friburgo of 1948, Costa established himself as the pre-eminent figure of Brazilian modernism.

Lucio Costa is best known for his urban plan for the new capital of Brasilia, having won the job in a 1957 public competition. Created from scratch in Brazil's hinterland and 'open for business' in less than three years, Brasilia is both famous and infamous. Costa's Plano Piloto (Pilot Plan) for Brasilia is in the shape of an irregular cross, suggesting an airplane or dragonfly, and is more legible from the sky than from ground level. Costa's own Parque Guinle project was the model for Brasilia's many residential tower-in-a-park superblocks, and Costa specified the color of the bus drivers' uniforms: dark grey, and with a manditory cap.

Although named as an UNESCO World Heritage Site in 1987, the city is notorious for its windswept emptiness and anti-pedestrian layout. Some streets are badly lit because the height and spacing of light standards were not changed with the advent of mercury-vapor bulbs, and World Heritage Site designation has prevented remediation. Most streets have cloverleafs or traffic circles rather than intersections or traffic lights, so cars have no reason to stop. It is virtually impossible for pedestrians to travel east and west in the city without crossing the axial expressway and risking their lives. Costa was responsible for the layout, and Oscar Niemeyer responsible for many of the landmark buildings, and there were disputes between the two afterwards.