Geoffrey Nielsen Ostergaard (25 July 1926 – 22 March 1990) was a British political scientist best known for his work on the connections between Gandhism and anarchism, on the British co-operative movement, and on syndicalism and workers' control. His books included The Gentle Anarchists: A Study of the Sarvodaya Movement for Non-Violent Revolution in India (1971), coauthored with Melville Currell, and Nonviolent Revolution in India (1985), both dealing with the Sarvodaya movement. He spent the majority of his academic career at the University of Birmingham.