The concept of fear (or anxiety) is of great importance in existential philosophy. Existentialists give fear a positive connotation: we need it in order to pull a person out of a thoughtless life. Fear is like fire, it burns everything unimportant and temporary; only in it is true existence revealed. The first to write about this was Søren Kierkegaard (1813–1855), a Danish philosopher and psychologist, the founder of existentialism. Then the topic was continued by other representatives of this trend, in particular, Rollo May (1909–1994), an American philosopher and psychologist, theorist of existential psychology. It examines the main problems of human existence: anxiety and fear, freedom, responsibility and fate, in addition, it gives a historical overview of the development of these ideas in scientific thought.