Diary of a Bad Year is a book by South African-born Nobel laureate J. M. Coetzee.

It was released by Text Publishing in Australia on 3 September 2007, in the United Kingdom by Harvill Secker (an imprint of Random House) on 6 September, and in the United States on 27 December.

The protagonist, called Señor C. by the other characters, is an ageing South African writer living in Sydney, Australia.

The novel consists of his essays and musings alongside diary entries by both Señor C. and Anya, a neighbour whom he has hired as a typist.

The essays, which take up the larger part of each page, are on wide-ranging topics, including the politics of George W. Bush, Tony Blair, Guantánamo Bay, and terrorism.