Movement originating with Soren Kierkegaard (1813-1855) and continuing later with Karl Jaspers (1883-1969), Gabriel Marcel (1889-1973), Martin Heidegger (1889-1976), Jean-Paul Sartre (1905-1980), and various others, though it has had little influence in English-speaking philosophy. Fyodor Dostoevsky (1812-1881) and Friedrich Nietzsche (1844-1900) are sometimes included.
The former, which is partly an actual condition of humans and partly something to be pursued, is essentially open-ended and free from determination by any already existing essence: 'existence precedes essence'. Hence the emphasis on freedom, choice and responsibility, evasion of which by relapsing into a 'thing-like' state (or trying to do so) is Sartrian 'bad faith'.
Consciousness of this total open-endedness leads to dread (despair, anguish, angst, angoisse). In studying being, existentialists have been influenced by phenomenology.
N Langiulli, ed., The Existentialist Tradition (1971); selections, those from Abbagnano, Buber, Marcel, and Sartre being perhaps the most accessible