Igor Youriévitch Bogdanoff (French pronunciation: [iɡɔʁ juʁi.evitʃ bɔɡdanɔf]; 29 August 1949 – 3 January 2022) and Grégoire "Grichka" Youriévitch Bogdanoff (French: [ɡʁeɡwaʁ ɡʁiʃka]; 29 August 1949 – 28 December 2021), alternatively spelled Bogdanov, were French twin television presenters, producers, and essayists who presented a variety of programmes in science fiction, popular science, and cosmology. They were involved in a number of controversies, the most notable being the Bogdanov affair. It brought to light how they received Ph.D. degrees based on largely nonsensical physics papers that were nonetheless peer-reviewed and published in reputable scientific journals. In their later years, they were also the subject of numerous internet memes, particularly in the cryptocurrency community.