Krassimir Todorov Atanassov (Bulgarian: Красимир Тодоров Атанасов; 23 March 1954, Burgas, Bulgaria) is a Bulgarian mathematician, Corresponding member of the Bulgarian Academy of Sciences (2012). He is best known for introducing the concepts of and Intuitionistic fuzzy sets, which are extensions of the concepts of Petri nets and Fuzzy sets, respectively.