Rem Koolhaas (born Remment Lucas Koolhaas, November 17th, 1944) is a Dutch architect, architectural theorist and urbanist. Koolhaas was born in Amsterdam. Before becoming an architect, he studied scriptwriting at the Netherlands Film and Television Academy. He then worked as a journalist for the Haagse Post. In 1968, he started to study architecture at the Architectural Association School of Architecture in London. After graduation he went to Cornell University in Ithaca, New York to study with O.M. Ungers. Koolhaas first came to public and critical attention with OMA (The Office for Metropolitan Architecture), the office he founded in 1975 together with architects Elia Zenghelis, Zoe Zenghelis and (Koolhaas's wife) Madelon Vriesendorp in London. They were later joined by one of Koolhaas's students, Zaha Hadid - who would soon go on to achieve success in her own right.

The first large commission by OMA to be built was the Kunsthal in Rotterdam (1992). At that time Koolhaas already built a reputation as a prolific writer and architecture critic. With the Kunsthal project, Koolhaas attempted to put into practice many of the findings he made in his first book Delirious New York which was written in 1978 while he was a visiting scholar at the Institute for Architecture and Urban Studies in New York, directed by Peter Eisenman. In Delirious New York Koolhaas celebrates the "chance-like" nature of city life: "The City is an addictive machine from which there is no escape". As Koolhaas himself has acknowledged, this approach had already been evident in the Japanese Metabolist Movement in the 1960s and early 1970s.

Koolhaas' writing gained him recognition as a visionary early in his career; later the combination of architecture, urban planning, research and writing solidified Rem Koolhaas' reputation. However with many major projects completed, it is not that easy to recognize an identifiable style. He considers that a compliment because working in so many different environments and under so many different conditions, the finished work must be different too. He's been called a modernist by some, and a de-constructivist by others, but he really defies categorization. In 1995, another book S,M,L,XL summarized the work of OMA and established connections between contemporary society and architecture. In 2003, an exhibition of his works and organised by OMA was shown under the name Content, at the Neue Nationalgalerie in Berlin. In conjunction with the exhibition, a book of the same name was published by Taschen Books. Content illustrates the ways that Rem Koolhaas and OMA interact with the world and how the world in turn influences their work.

Since 1995, Koolhaas is a professor at Harvard University where he leads a student-based research group that studies different issues affecting the urban condition. The projects include a study of five cities in the Pearl River Delta in China; a study called The Roman System, focusing on the ancient Roman city; Shopping, an analysis of the role of retail consumption in the contemporary city; and a study of the African city, focusing specifically on Lagos, Nigeria.

Currently, Rem Koolhaas is heading the work of OMA as well as AMO - the conceptual branch of OMA, a think tank focused on social, economic, and technological issues. The work of Rem Koolhaas and OMA has been celebrated as well by several international awards, including the Pritzker Architecture Prize (2000) and the RIBA Gold Medal (2004).