Bent Flyvbjerg (born 1952) is a Danish economic geographer. He is Professor of Major Programme Management at Oxford University's Saïd Business School and the first Director of the University's BT Centre for Major Programme Management. He was previously Professor of Planning at Aalborg University, Denmark and Chair of Infrastructure Policy and Planning at Delft University of Technology, The Netherlands. He is a fellow of St Anne's College, Oxford.

Flyvbjerg is the author or editor of 10 books and more than 200 papers in professional journals and edited volumes. His publications have been translated into 19 languages. His research has been covered by Science, The Economist, The New York Times, The Wall Street Journal, The Financial Times, The BBC, CNN, Charlie Rose, and many other media.

Flyvbjerg received his Ph.D. in urban geography and planning from Aarhus University, Denmark. He has written extensively about megaprojects, decision making, city management, and philosophy of social science. He was a member of the Danish Infrastructure Commission and a director of the Danish Court Administration. He has twice held the Fulbright Scholarship. Bent Flyvbjerg was knighted in the Order of the Dannebrog in 2002.

His research has shown that competition between megaprojects and their sponsors creates political and organizational pressures that leads to the consistent overestimating of project benefits and the underestimating of project costs. The best megaprojects do not get implemented, but rather the ones that look best on paper. He argues that the ones that look best on paper are the ones for which costs and benefits have been misrepresented the most.