Mostly the author, with possible editor override. In my case, my working title got changed, and it was certainly a net improvement. My original title was 'Pseud

Mostly the author, with possible editor override. In my case, my working title got changed, and it was certainly a net improvement. My original title was 'Pseudorandomness', by analogy with the computer science concept. Now, it's 'Chaos Monkeys' (by analogy with the software tool). Definitely an improvement.