On August 4, 2020, prof. dr hab. Jan Strelau, full member of the Polish Academy of Sciences, chairman of the Council of Scientific Societies at the Presidium of the Polish Academy of Sciences in the 2003-2006 term passed away. He was an outstanding representative of Polish and world psychologists, the creator of the Regulatory Theory of Temperament, an authority in the fields of research on temperament, personality, individual differences and behavior genetics.