Shan Ratnam, Sri Lankan physician and academic (d. 2001)
Emeritus Professor Sittampalam Shanmugaratnam (4 July 1928 – 6 August 2001), also known as Shan Ratnam, was a Singaporean obstetrician and gynaecologist.

He was professor and head of the department of Obstetrics and Gynaecology of the National University Hospital of Singapore and specialized in human reproduction research. He was a medical pioneer and leader in the field of Obstetrics and Gynaecology, both in Singapore and internationally. At the peak of his career, he was the Secretary-General of the Asia and Oceania Federation of Obstetrics and Gynaecology (AOFOG) and the President of the International Federation of Obstetrics and Gynaecology.

His work placed Singapore at the forefront in the international medical arena and established himself as a prominent figure in world of Obstetrics and Gynaecology. His work on contraception also contributed to Singapore's success in population control. The National University Hospital research laboratory for prostaglandin research was initiated and propelled by his vision and energy. He was also the founder of the IVF programme for childless couples.