Friedrich Hölderlin and Friedrich Nietzsche were both important influences on Heidegger, and many of his lecture courses were devoted to one or the other, especially in the 1930s and 1940s.
The lectures on Nietzsche focused on fragments posthumously published under the title The Will to Power, rather than on Nietzsche's published works.
Heidegger read The Will to Power as the culminating expression of Western metaphysics, and the lectures are a kind of dialogue between the two thinkers.

The fundamental differences between the philosophical delineations of Heidegger and Adorno can be found in their contrasting views of Hölderlin's poetical works and to a lesser extent in their divergent views on German romanticism in general.
For Heidegger, Hölderlin expressed the intuitive necessity of metaphysical concepts as a guide for ethical paradigms, devoid of reflection.
Adorno, on the other hand, pointed to the dialectic reflection of historical situations, the sociological interpretations of future outcomes, and therefore opposed the liberating principles of intuitive concepts because they negatively surpassed the perception of societal realities.
Nevertheless, it was Heidegger's rationalization and later work on Hölderlin's poems as well as on Parmenides ("For to be aware and to be are the same," DK B 3) and his consistent understanding of Nietzsche's thought that formed the foundation of postmodern existentialism.

This is also the case for the lecture courses devoted to the poetry of Friedrich Hölderlin, which became an increasingly central focus of Heidegger's work and thought.
Heidegger grants to Hölderlin a singular place within the history of being and the history of Germany, as a herald whose thought is yet to be "heard" in Germany or the West.
Many of Heidegger's works from the 1930s onwards include meditations on lines from Hölderlin's poetry, and several of the lecture courses are devoted to the reading of a single poem (see, for example, Hölderlin's Hymn "The Ister").
Friedrich Hölderlin and Friedrich Nietzsche were both important influences on Heidegger, and many of his lecture courses were devoted to one or the other, especially in the 1930s and 1940s. The lectures on Nietzsche focused on fragments posthumously published under the title The Will to Power, rather than on Nietzsche's published works. Heidegger read The Will to Power as the culminating expression of Western metaphysics, and the lectures are a kind of dialogue between the two thinkers.
The fundamental differences between the philosophical delineations of Heidegger and Adorno can be found in their contrasting views of Hölderlin's poetical works and to a lesser extent in their divergent views on German romanticism in general. For Heidegger, Hölderlin expressed the intuitive necessity of metaphysical concepts as a guide for ethical paradigms, devoid of reflection. Adorno, on the other hand, pointed to the dialectic reflection of historical situations, the sociological interpretations of future outcomes, and therefore opposed the liberating principles of intuitive concepts because they negatively surpassed the perception of societal realities. Nevertheless, it was Heidegger's rationalization and later work on Hölderlin's poems as well as on Parmenides ("For to be aware and to be are the same," DK B 3) and his consistent understanding of Nietzsche's thought that formed the foundation of postmodern existentialism.
This is also the case for the lecture courses devoted to the poetry of Friedrich Hölderlin, which became an increasingly central focus of Heidegger's work and thought. Heidegger grants to Hölderlin a singular place within the history of being and the history of Germany, as a herald whose thought is yet to be "heard" in Germany or the West. Many of Heidegger's works from the 1930s onwards include meditations on lines from Hölderlin's poetry, and several of the lecture courses are devoted to the reading of a single poem (see, for example, Hölderlin's Hymn "The Ister").
Martin Heidegger