Alexander Cunningham: A British engineer and archaeologist, he was appointed the inaugural Director-General of the Archaeological Survey of India (ASI) in 1871. His efforts established the groundwork for systematic archaeological research in India. Cunningham is recognized for his comprehensive surveys, documentation, and excavations of many sites, earning him the title "Father of Indian Archaeology."
John Marshall: A subsequent Director-General of the ASI, he is credited with overseeing the excavations of Harappa and Mohenjo-Daro in the 1920s, leading to the discovery of the Indus Valley Civilization. While his contributions were significant, he was not the first director general.
Daya Ram Sahni: An Indian archaeologist, he is noted for his work on the Indus Valley Civilization, specifically the excavation of Mohenjo-Daro. Sahni worked under John Marshall and did not hold the position of director general.
S.N. Roy: A scholar and historian, his primary contributions were in history, not archaeology. He did not serve in any capacity at the ASI.