Sentinel is a fictional character in the X-Men comic book series. They are giant robots created by humans to hunt down and capture mutants, often serving as the main antagonists in X-Men storylines. The Sentinels were designed by Dr. Bolivar Trask and are capable of adapting to the powers of the mutants they are hunting, making them an extremely dangerous threat. They have been responsible for the deaths of many mutants, including several members of the X-Men. The Sentinels have also been depicted in various X-Men adaptations, including movies and TV shows, as well as in video games. Overall, Sentinel is a powerful and deadly enemy of the X-Men, representing the ongoing conflict between mutants and humans in the Marvel universe.