The Day the Earth Stood Still (2008)

In 1928, a mountaineer encounters a glowing sphere of ice and finds himself waking up with a scar. In the present day, a scientist is brought together with other experts to deal with a large object heading towards Manhattan. The object turns out to be a spaceship and a being named Klaatu emerges along with a giant robot. Klaatu is shot but is revived and reveals that he is a representative of alien races sent to talk to world leaders. After escaping from captivity, Klaatu meets with another alien who decides to stay on Earth but Klaatu decides that humanity should be exterminated due to their destructive nature. Meanwhile, the robot transforms into nanites and starts destroying everything in its path back to Manhattan. Dr. Benson tries to convince Klaatu that humans can change, and they rendezvous with other people who also try to convince Klaatu to save humanity. Klaatu sacrifices himself to stop the robot, saving humanity but leaving Earth's technology useless.