Valak was the primary antagonist of the Star Trek: The Next Generation novel The Romulan Prize.
He was a male Romulan who descended from Romulans who made their home in the northern regions of Romulus. Born on the remote colony world Abraxas IX, he was raised by his father in the traditional Romulan ways, which themselves were heavily influenced by their Vulcan cousins. Trained in the additional hunting arts, he developed a healthy respect for prey, knowing that to not study prey before trying to hunt them could result in disaster since prey could often injure or even kill an overconfident individual. Learning the habits of the syrinx enabled him to take several of them over the years when just surviving an encounter with a syrinx was considered quite the accomplishment.
Like many Romulans, Valak grew up believing in the inherent superiority of the Romulan people, and believed that the Romulans were destined to rule over all the other races in the galaxy. As a young man he enrolled in the acadmey. During his time there he made an extensive study of the Federation, especially the humans. Despite being seen as a bit of an eccentric by his classmates due to his respect towards the humans, papers he submitted to the academy were well received.
Rising through the ranks, Valak eventually came to the attention of the Praetor Darok, who summoned him to a meeting in 2368. At that meeting the two discussed the humans and the Federation. Convinced that the young man would make a good commander for a mission to uncover the mystery of Hermeticus II, who the Romulans had learned of from a spy. Darok named Valak the commander of the new D'Kazanak-class vessel IRW Syrinx.
Valak took his new command to a location near the neutral zone. Faking a disaster, Valak sent a distress call that was picked up by the USS Enterprise-D. Capturing the Enterprise Valak took a large number of the Enterprise crew hostage. While Picard managed to delete classified information from the computer system, Valak still got the coordinates for Hermeticus II and had a course set for there. He intended to find out what was going on at that world, sell the Enterprise crew into slavery, and then use his successes to propel himself into a high ranking government position.
Things did not work out as planned though for Valak when they arrived at Hermeticus II, which was a huge interstellar starship crewed by a race of telepathic shapeshifters called Ambimorphs. They had been encountered by the crew of the Federation starship USS Independence some years earlier. Due to being accidently infected with a virus carried by the Ambimorphs, the crew was never able to leave. Four Ambimorphs left in one of the Independence shuttles, assuming the identities of crew members who had no families and had died. The four were later found "dead" by another Federation starship. Taken back to Earth the four slipped away and infiltrated the Federation, assuring Hermeticus II and all other information on their world was was highly classified, then proceeded to engage in long term study of the Federation with the idea of preparing for peaceful first contact.
The Ambimorphs took more and more of the Romulan crew hostage. An Ambimorph posing as Valak was able to get large numbers of Romulans to beam down to Hermeticus. Valak himself soon followed, with Picard as a hostage. At an opportune moment Picard was able to turn the tables on Valak, injure him, and take him prisoner with the assistance of the Ambimorphs. Meanwhile in orbit the Ambimorphs helped the Enterprise crew retake their starship and capture the Syrinx.
Speaking with Commander Morgan Llewellyn, the former first officer of the Independence and leader of the colony of the crew and their descendants, Picard and his crew learned more about what had happened. Realizing that their secret was about to be exposed, the Ambimorphs decided to leave for home, a journey that would take a very long time, and take the Romulans with them to prepare for peaceful first contact with the Romulan Star Empire. The Independence and Syrinx would be destroyed in a matter that made it look like the two ships perished in battle. A group of Ambimorphs was tasked with taking a shuttle with "survivors" which would include Ambimorphs disguised as Valak and the designer of the Syrinx - who would tell the Romulan government that the Syrinx suffered from serious design flaws and no more ships of that type should be built.
Valak knew that with the failure of his mission at the very least his military career would have been over had he returned to Romulus. Before being beamed to the surface of Heremeticus II Valak admitted to Picard that he had underestimated Picard and his crew. Meanwhile one of the Ambimorphs turned into an exact duplicate of Valak. He told Valak that he would pursue a scholarly career on Romulus, and he hoped that Valak would do the same during his time with his people. Picard told Valak that he and his crew were being given a unique opportunity, and that Valak would have the chance to conduct research that might someday greatly benefit his people. Taking his leave, Valak told Picard he had a good crew and meeting them was stimulating.
While being more than the common thug that most of his fellow officers seemed to be, Valak was still a young man who had never suffered any serious setbacks or defeats in his career. Valak only knew about the Federation and humans through academic research, Valak had little practical experience with command. He also suffered from a need for respect from those he bested, especially experienced officers like Picard. Picard and the Enterprise crew were able to use Valak's weaknesses along with those of his crew to their advantage in retaking their ship.