Existential phenomenology
Existential phenomenology is a philosophy inspired by Martin Heidegger's 1927 work Sein und Zeit (Being and Time) and influenced by the existential work of Søren Kierkegaard and the phenomenological work of Edmund Husserl.
In contrast with his former mentor Husserl, Heidegger 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 contrast with the philosopher Kierkegaard, Heidegger wanted to explore the problem of Dasein existentially (existenzial), rather than existentiell]]y (existenziell) because Heidegger argued Kierkegaard had already described the latter with "penetrating fashion".
Development of existential phenomenology
Besides Heidegger, other existential phenomenologists were Hannah Arendt, Emmanuel Levinas, Gabriel Marcel, Jean-Paul Sartre, Maurice Merleau-Ponty, and Samuel Todes.
Other disciplines
Existential phenomenology extends also to other disciplines. For example, Leo Steinberg's momentous essay "The Philosophical Brothel" describes Picasso's Les Demoiselles d'Avignon in a perspective which is existential-phenomenological.