Professor Andrzej Udalski, PhD (born 22 January 1957 in Łódź, Poland) is a Polish astronomer and director of the Astronomical Observatory of the University of Warsaw. He is also head of the Department of Observational Astrophysics at Astronomical Observatory, the head and project manager of the Optical Gravitational Lensing Experiment, and editor of the quarterly journal Acta Astronomica.
He graduated from the Faculty of Physics, University of Warsaw in 1980. In that same year, he was employed at the Astronomical Observatory of the University of Warsaw. He received his doctorate in 1988 and then completed a two-year Postdoctoral Research Associate at York University in Toronto, Canada.
In April 1992, he created the OGLE project that is still in existence. In 1995-1996, he took part in the construction of the Warsaw Telescope at Las Campanas Observatory in Chile. In 2001, he built a wide-angle mosaic CCD camera with more than 65 million light-sensitive elements. Along with the OGLE team, he is also a co-discoverer of 14 extra-solar planets discovered by the technique of gravitational microlensing.
He has authored or co-authored nearly 400 scientific papers. In 1996, he was honored by the Prime Minister for outstanding scientific achievements. In 2002, he won the prize of the Foundation for Polish Science (the so-called "Polish Nobel"). In 2009, he received a 2.5 million Euro grant from the program Ideas of the European Research Council that aims to support innovative research projects.