Alonso Fernández de Avellaneda: this is the name behind the Segundo tomo del ingenious hidalgo don Quijote de la Mancha qui contiene la tercera salida y es la quinta parte de sus aventuras, published in Terragona in 1614.
This name is a pseudonym concealing the real name of a writer whose identity, still now, remains unknown despite the several attempts made by scholars to determine who he was: the intel gathered so far seem to lead to a learned figure, very close to nobility, a skilled and experienced writer.
Cervantes, following the publication and the success of the first part of the Don Quixote, waited a long time before publishing the second part, which was preceded by the release of this apocryphal text.
As a result, Cervantes' second book begins with a prologue in which the author alludes to Avellaneda's Don Quixote and promises to cover, in this second part, all of the hidalgo's adventures up to his death and burial.
Avellaneda's Don Quixote, although not the result of Cervantes' genius, is considered an interesting novel and had considerable success: several editions have followed after the renowned edition of 1614 which brought exceptional luck to this text.