Jacobus Johannes Pieter Oud (1890–1963) was a Dutch architect and a key member of the De Stijl movement, known for his rational, geometric designs. As Rotterdam’s chief city architect, he played a major role in social housing projects, designing modernist landmarks like the Hook of Holland housing complex and the Kiefhoek housing estate. His early works were highly abstract and minimalist, influenced by Piet Mondrian and Theo van Doesburg, but later evolved to incorporate traditional materials and humanistic elements. Oud’s fusion of modernist aesthetics with practical urban solutions influenced European modernism and functionalist architecture.