Who did Wagner influence?
Hardly anyone who came after him was not in some way influenced by Wagner. He introduced a radical new way of approaching structure and harmony. Without Wagner’s (and Mahler’s) influence Schoenberg might not have taken that step further in his career and experimented with atonality and serialism (along with Webern and Berg after him). The young Dvořák was heavily influenced by Wagner (perhaps shown most strongly in the 3rd Symphony) as was, of course Bruckner, who idolised the older composer and even dedicated his own Third Symphony to him (complete with quotations from Wagner, expunged in later revisions). Even a composer as seemingly different from Wagner as Claude Debussy was initially strongly influenced by him – as one can tell in Debussy’s great opera ‘Pelleas and Melisande’. Hardly any composers in central Europe active between 1880 and 1910 were immune to Wagner’s influence to a greater or lesser extent. Strangely, I don’t hear Wagner in Mahler, who was such an individual voice