Target Earth

Target Earth is a 1954 alien invasion movie in which we gradually get to know the few people who missed the mass evacuation. Robots from Venus aren't the only danger, though, as the group members turn on each other and the military doesn't know there's anybody left in the target area.

part 1:

part 2:

1000 Misspent Hours says, "it accomplishes much more through subtlety than its budget would ever have allowed had its creators aimed for spectacle instead." Moria says, "The film has a great opening. ... Alas, once we see the robots -about 30 minutes into the film– Target Earth takes a nosedive."

Weird Wild Realm likes the robot and says,

And even though the robot appears to have been constructed from large biscuit-tins; flexi-ducts then spray-painted silver, it's even so a wonderful piece of art deco minimalism, inspiring many a child of the 1950s to build their own robot costume from cardboard boxes. ... Well acted, cool robots, with a more than adequate array of B-actors headed up by Richard Denning, & told with poker-faced conviction. Truly worthwhile.

TCM has information. Rotten Tomatoes has an audience score of 27%.