Existential phenomenology encompasses a wide range of thinkers who take up the view that philosophy must begin from experience like phenomenology, but argues for the inability of philosophers to themselves exit existence in order to view the human condition universally. 
In contrast with his former mentor Edmund Husserl, Heidegger (in his Being and Time) put ontology before epistemology and thought that phenomenology would have to be based on an observation and analysis of Dasein ("being-there"), human being, investigating the fundamental ontology of the Lebenswelt (lifeworld, Husserl's term) underlying all so-called regional ontologies of the special sciences. In Heidegger's philosophy, people are thrown into the world in a given situation, but they are also a project towards the future, possibility, freedom, wait, hope, anguish. In contrast with the philosopher Kierkegaard, Heidegger wanted to explore the problem of Dasein existentially (existenzial), rather than existentielly (existenziell) because Heidegger argued Kierkegaard had already described the latter with "penetrating fashion". Most existentialist phenomenologists were concerned with how we are constituted by our experiences and yet how we are also free in some respect to modify both ourselves and the greater world in which we live.
In Heidegger's language that we are "thrown into the world" Jean-Paul Sartre's that "existence precedes essence." Both of these point out that who any individual is, is a matter of the social, historical, political, and economic situation into which he or she is born. This frees phenomenology from needing to find a universal ground to all experience, since it will always be partial and influenced by the philosopher's own situation. Maurice Merleau-Ponty argued that the lesson of Husserl's reduction is that "there is no complete reduction" because even phenomenologists cannot resist how they have been shaped by their history, culture, society, and language.Simone de Beauvoir explored how greatly norms of gender shapes the very sense of self that women have, in distinction from men, in her work The Second Sex. Hannah Arendt discusses how totalitarian regimes in the 20th century presented entirely new regimes of terror that shaped how people understand political life in her work The Human Condition.Frantz Fanon explored the legacy of racism and colonialism on the psyches' of black men.However, they all in different ways also stressed the freedom which humans have to alter their experiences through rebellion, political action, writing, thinking, and being. If we are constituted by the human social world, then it is only humans that created it and can create a new world if they take up this task.
Besides Heidegger, other existential phenomenologists were Hannah Arendt, Karl Jaspers, Emmanuel Levinas, Gabriel Marcel, Jean-Paul Sartre, Simone de Beauvoir, Frantz Fanon, Maurice Merleau-Ponty, Enzo Paci and Samuel Todes.
Existential phenomenology extends also to other disciplines. For example, Leo Steinberg's essay "The Philosophical Brothel" describes Picasso's Les Demoiselles d'Avignon in a perspective that is existential-phenomenological. It has also impacted architectural theory, especially in the phenomenological and Heideggerian approaches to space, place, dwelling, technology, etc. In literary theory and criticism, Robert Magliola's Phenomenology and Literature: An Introduction (Purdue UP, 1977; rpt. 1978) was the first book to explain to Anglophonic academics--systematically and comprehensively--the range of literary theories and practices identified with "phenomenological literary criticism" on the Continent. The practices of the francophonic Geneva School (-of literary criticism), those of the Swiss-German theorist and critic Emil Staiger, and those of several other theorists/critics, are explained in detail. The influences of the phenomenological theorist Roman Ingarden, of the early-phase (existentialist-) Martin Heidegger, and of Mikel Dufrenne receive a treatment over 100 pages long all-told. The polemics involving phenomenology and its opponents are addressed in separate chapters, entitled respectively "Phenomenology Confronts Parisian Structuralism," and "The Problem of Validity in E. D. Hirsch and Husserl. The 1978 rpt. of Magliola's book features on its back cover very strong endorsements from Robert Scholes, Eugene Kaelin, Monroe Beardsley and Ralph Freedman.