Henrietta Lacks (born Loretta Pleasant; August 1, 1920 – October 4, 1951) was an African-American woman whose cancer cells are the source of the HeLa cell line, the first immortalized human cell line and one of the most important cell lines in medical research. An immortalized cell line reproduces indefinitely under specific conditions, and the HeLa cell line continues to be a source of invaluable medical data to the present day.

Lacks was the unwitting source of these cells from a tumor biopsied during treatment for cervical cancer at Johns Hopkins Hospital in Baltimore, Maryland, U.S., in 1951. These cells were then cultured by George Otto Gey, who created the cell line known as HeLa, which is still used for medical research. As was then the practice, no consent was required to culture the cells obtained from Lacks's treatment. Neither she nor her family were compensated for the extraction or use of the HeLa cells.

Even though some information about the origins of HeLa's immortalized cell lines was known to researchers after 1970, the Lacks family was not made aware of the line's existence until 1975. With knowledge of the cell line's genetic provenance becoming public, its use for medical research and for commercial purposes continues to raise concerns about privacy and patients' rights.