| Honorific Prefix: | Admiral |
| Office1: | 16th Chief of the Naval Staff |
| Termstart1: | 30 December 1998 |
| Termend1: | 29 December 2001 |
| President1: | K. R. Narayanan |
| Primeminister1: | Atal Bihari Vajpayee |
| Predecessor1: | Vishnu Bhagwat |
| Successor1: | Madhvendra Singh |
| Sushil Kumar Isaacs | |
| Honorific Suffix: | PVSM, UYSM, AVSM, NM |
| Birth Place: | Neyyoor, Kanyakumari district, Tamil Nadu, India |
| Death Place: | New Delhi |
| Allegiance: |  India |
| Serviceyears: | 1961 - 2001 |
| Rank: | Admiral |
| Commands: | Chief of the Naval Staff Southern Naval Command FORTAN |
| Battles: | Goa Liberation of 1961 Indo-Pakistan War of 1965 Indo-Pakistan War of 1971 Kargil War |
| Awards: | Param Vishisht Seva Medal Uttam Yudh Seva Medal Ati Vishisht Seva Medal Nao Sena Medal |
Admiral Sushil Kumar Isaacs, PVSM, UYSM, AVSM, NM (died 27 November 2019) was an Indian Navy Admiral who served as Chief of Naval Staff (CNS) of the Indian Navy. He was the Director of Naval Operations during Operation Pawan and Operation Cactus and was the CNS during the Kargil War.
A native of Neyyoor (Nagercoil), he joined the Indian Navy and was commissioned in 1961. He ceased to use his surname of Isaacs[1] because it caused confusion with his brother, who shares the same initials and is also a naval officer.[2] He was an alumni of The Bishop's School, Pune
A specialist in hydrography and amphibious warfare,[3] Kumar was also a qualified air warfare instructor. He was an alumnus of the National Defence College and was an instructor at the Defence Services Staff College, Wellington. His training abroad included a deputation to the Royal Navy on board in 1963 and a course in amphibious warfare with the US Navy at Coronado, California, in 1976.[4] He participated in the 1961 invasion of Goa and in both the Indo-Pakistan wars of 1965 and 1971. He was awarded the Nao Sena Medal for gallantry whilst in command of INS Ghorpad.
Kumar was promoted to substantive commander on 1 January 1977 and to captain on 1 January 1983.[5] [6] As Director of Naval Operations, he was decorated with the Uttam Yudh Seva Medal for his exceptional conduct in Operation Pawan and in Operation Cactus (Liberation of Maldives).
Kumar was promoted to substantive rear admiral on 6 July 1990.[7] Kumar held operational commands and important posts such as the Vice Chief of Naval Staff, the Flag Officer Commanding Maharashtra Naval Area (FOMA), Commander of the Flotilla in Mumbai and Fortress Commander, Andaman and Nicobar Islands (FORTAN). He was the Flag Officer Commanding-in-Chief Southern Naval Command in Kochi, before being appointed the Chief of Naval Staff. Sushil Kumar assumed charge of the Indian Navy, as the 16th Chief of Naval Staff, on 30 December 1998. During his tenure as CNS, He was the highest-decorated serving officer in the Indian Navy, and he retired on 29 December 2001. He was a keen yachtsman and played polo on the international circuit, for which he had an international rating of 4+ goals.[4]
Kumar died on 27 November 2019 at the Indian Army Research and Referral Hospital, Delhi at the age of 79. Prime Minister Narendra Modi expressed his condolences upon this.[8] [9]