There are at least a few famous authors who are famous for writing in second or third languages:
Nabokov, Kerouac, Milan Kundera, Samuel Beckett; but there are many more.
In general-- members of diasporas, members of first nation groups, members of cultures where bilingualism and trilingualism are common, persons who immigrated at a young age. And some of those authors have very much contributed to the sense that “Literatures in English” should be pluralized.
