Murphy is the magician whose talent makes everything go wrong that possibly could. He was the rival of King Roogna and first appeared in Castle Roogna. To determine the next king of Xanth, Roogna would built Castle Roogna, and Murphy would try to stop him. After Roogna successfully completed the construction of the castle and claimed the throne, Murphy banished himself to the Brain Coral's pool.
After Murphy and Vadne escaped the Brain Coral's pool during the Time of No Magic, they were waylaid by Com Pewter who made them a deal. It would help them escape to Mundania in return for the services of their first born.
Murphy and Vadne did everything they could to keep Grey from knowing anything about or going to Xanth. They did not know Grey was a magician. Murphy used his talent to curse the onus Com Pewter had on Grey.
Murphy's talent (and name) is based on Murphy's Law: Everything that can go wrong, will go wrong
Murphy is a major character in Castle Roogna.