Peripheral Works

I've been pondering the idea of artists or thinkers who don't work in a particular genre or medium, but nonetheless have a specific appeal to people who do. My own examples for contemporary poetry might include the philosopher Ludwig Wittgenstein (as Marjorie Perloff notes, in Wittgenstein's Ladder) and the science fiction writer Samuel Delany.

What have your experiences been of this effect? Who, for you, are some other striking examples of, say, a poet's philosopher? What, in your opinion, serves to endear/associate that person to poets? And vice-versa?