An Italian designer, one of the key figures in mid-20th century lighting design. In the 1930s, he began working in Milan, where in 1946 he founded the company Arredoluce, which became an important platform for experimentation with lighting and form. Lelii specialized in the development of lamps, combining an engineering approach with attention to plasticity and materials. His works are characterized by the use of brass, painted metal, and glass, as well as expressive structural solutions. Many objects are built on the principle of balancing and movable elements, allowing for changes in light direction and object configuration. Within Arredoluce, he collaborated with leading architects and designers of his time, creating both serial models and bespoke solutions for interiors.