Santo vs. the Martian Invasion (1967)

Original title: Santo el enmascarado de plata vs. la invasión de los marcianos

In this Mexican sci-fi fantasy, big beefy Martians invade the earth. Ostensibly, they have come to warn people about the dangers of nuclear testing and exploring space, but their real mission becomes manifest when they begin using their special powers and gadgets to exploit weak earthlings.