Muhammad Ainun Nadjib, best known as Emha Ainun Nadjib or Cak Nun/Mbah Nun, is an Indonesian poet, essayist, kyai, ulama, and humanist. Born in Jombang, East Java, Nadjib began writing poetry while living in Yogyakarta, publishing his first collection in 1976. He became one of the city's predominant poets by the late 1980s, and by then had also began writing essays. He is the leader of the Kiai Kanjeng group, which stages dramas and musical performances on religious themes.
Early poems by Nadjib have elements of social criticism. However, more prominent are Islamic values, variously described as santri or Sufi. Islam is also a common subject for his essays. His writings have taken a variety of forms, including poetry, essays, novels, and short stories.