Lucian's True Story by Lucian of Samosata.
This is, quite possibly, the very first sci-fi book. It was written in response to the popular travel journals at the time, that were often filled with lies in their description of fantastic creatures found in foreign lands.
Contemporary Fiction: A Very Short Introduction by Robert Eaglestone.
This series is a hit or miss. Some Very Short Introductions are great, but others awful. So far I'm very happy with this one, it is a reasonable and brief description of the main elements of contemporary fiction, and how it makes use of modernist and postmodernist tricks to address contemporary problems.
On Poetry and Poets, by T.S. Eliot
A collection of essays. It's hard to go wrong with T.S. Eliot. I'm always impressed by his brief and poignant writing, I think it may be what happens what a poet writes essays: brevity and precision is of the essence.
Una Pasión Prohibida, by Christina Peri Rossi
It's a collection of short stories by Cervantes-Prize winner Christina Peri Rossi. They're alright, but so far I'm not very impressed. I cannot help to compare with another collection of short stories of hers, Desastres Íntimos, which I liked more.