Pseudonymous Bosch is the pen name of Raphael Simon, born October 25, 1967, a writer known for his fiction for young readers. His most recognized works include The Secret Series and The Bad Books series, along with The Unbelievable Oliver mysteries and several standalone titles. Simon, whose parents were also writers, attended Yale and later earned a Master's degree in Comparative Literature from UC Irvine. He also taught at various colleges in California before focusing on his writing career. He has since revealed his identity as Raphael Simon, and currently resides in Pasadena, California, with his husband and twin children.

Simon's career began with screenwriting, including work on the Nickelodeon series Rocket Power. He transitioned to novels, with his first book, "The Name of This Book Is Secret," published in 2007, originating as a series of letters. This book launched the widely successful Secret Series, which has been translated into numerous languages and sold millions of copies. He has also penned "Write This Book!," an interactive do-it-yourself mystery, and continued the Secret Series universe with "Bad Magic," the first in The Bad Books trilogy. More recently, he published "The Unbelievable Oliver and the Four Jokers" and its sequel, and in 2021, released "The Anti-Book" under his birth name, Raphael Simon.

The author known as Pseudonymous Bosch publicly acknowledged in May 2016 that he is, in fact, Raphael Simon. The pseudonym itself is a deliberate nod to the Renaissance artist Hieronymus Bosch, known for his fantastical and often unsettling imagery. It's also suggested that the name might playfully reference the fictional detective Harry Bosch, created by author Michael Connelly. This choice of a pseudonym, and the eventual reveal of his true identity, adds a layer of mystery to the author's persona, aligning with the often secretive and puzzle-filled narratives found within his books.

Raphael Simon, writing as Pseudonymous Bosch, has authored a significant body of work primarily aimed at young readers. His most celebrated contribution is "The Secret Series," a collection of five mystery novels that have achieved bestseller status and international recognition. These books, along with "The Bad Books" trilogy and "The Unbelievable Oliver" series, are characterized by intricate plots, engaging characters, and a sense of adventure. Simon has also explored interactive storytelling, as seen in "Write This Book!," a unique title that invites readers to actively participate in creating the narrative. His later work, "The Anti-Book," published under his real name, suggests a potential evolution in his literary focus or presentation.