Onkar Nath Srivastava (31 December 1942 – 24 April 2021) was an Indian material physicist, an Emeritus professor of Banaras Hindu University and the vice president for India and South Asia of the International Association for Hydrogen Energy, who is known for his contributions to the disciplines of nanotechnology and hydrogen energy. He is the author of two books and over 440 scientific papers and a recipient of several honors including Shanti Swarup Bhatnagar Prize, the highest Indian award in the science and technology categories. The Government of India awarded him the fourth highest civilian honour of the Padma Shri, in 2016, for his contributions to science and engineering.