The Ultraman (1966)

The series begins when the heroic alien Urutoraman pursues an alien menace to Earth. In the pursuit, he collides with Hiyata, an officer of the Science Patrol who is investigating the chase. To make amends for the accident, the alien gives his life force to the human along with his regular form and powers should he ever need it. Thus Hiyata is returned to Earth alive and merged with the alien. This linking proves to be a most fortuitous event as the monster being pursued is but the first of a wave of destructive monsters and aliens that attack the planet. Hiyata investigates sightings of these beasts as part of the Patrol who fights these threats with the advanced weapons at their disposal. However, the monsters often prove too strong for the Earth forces to stop. When that happens, Hiyata uses a beta capsule given to him by the alien. When he activates it, he transforms into the giant superhero, Urutoraman, who has the power necessary to protect Earth.