The appearance of a ghost in Alfred Brendel's poem ‘Brahms II’, set by Thomas Adès for baritone and orchestra in 2001, is not the first time Brahms the composer has been discussed with reference to the supernatural. In order to provide a hermeneutic interpretation of Adès's Brahms, op. 21, and an explanation of why Brahms continues to haunt composers of the twentieth and twenty-first centuries, this article draws on Derrida's notion of hauntology, exploring notions of the uncanny, late Brahms and Schoenberg's ‘Brahms the Progressive’.