Georgios Nikolaou Papanikolaou (Pap Test).

Georgios Nikolaou Papanikolaou ( 13 May 1883 – 19 February 1962) was a Greek pioneer in cytopathology and early cancer detection, and inventor of the "Pap smear".

Papanikolaou studied at the University of Athens, where he received his medical degree in 1904. Six years later he received his PhD from the University of Munich, Germany, after he had also spent time at the universities of Jena and Freiburg. In 1910, Papanikolaou returned to Athens and got married to Andromahi Mavrogeni and then departed for Monaco where he worked for the Oceanographic Institute of Monaco, participating in the Oceanographic Exploration Team of the Prince of Monaco (1911).

In 1913 he emigrated to the U.S. in order to work in the department of Pathology of New York Hospital and the Department of Anatomy at the Cornell Medical College Cornell University.

He first reported that uterine cancer could be diagnosed by means of a vaginal smear in 1928, but the importance of his work was not recognized until the publication, together with Herbert Frederick Traut (1894–1963), of Diagnosis of Uterine Cancer by the Vaginal Smear in 1943. The book discusses the preparation of vaginal and cervical smears, physiologic cytologic changes during the menstrual cycle, the effects of various pathological conditions, and the changes seen in the presence of cancer of the cervix and of the endometrium of the uterus. He thus became known for his invention of the Papanicolaou test, commonly known as the Pap smear or Pap test, which is used worldwide for the detection and prevention of cervical cancer and other cytologic diseases of the female reproductive system.

In 1961 he moved to Miami, Florida, to develop the Papanicolaou Cancer Research Institute at the University of Miami, but died there on 19 February 1962 prior to its opening.

Papanicolaou was the recipient of the Albert Lasker Award for Clinical Medical Research in 1950.

Papanikolaou's portrait appeared on the obverse of the Greek 10,000-drachma banknote of 1995–2001, prior to its replacement by the euro.

In 1978 his work was honored by the U.S. Postal Service with a 13-cent stamp for early cancer detection.