The villain in question is a large, blue-black robot that seems to operate as some sort of assassin or the like. I don't think it's a criminal mastermind type like Ultron, etc. It could fly, and its primary weapon was the ability to emit intense radiation (gamma rays?) from its eyes. It also had a design flaw of sorts. There was a small slot/opening at the back of its head, that could be exploited to defeat it. I remember reading about this villain in two separate Marvel Comics that were in my older brother's collection.
In the first one, the robot attacks Nick Fury aboard the SHIELD flying fortress (or whatever it is called). The bot smashes through an exterior wall, catching Fury off-guard. Fury battles with the robot, using his wits and several gadgets he conveniently been issued by a Bond movie Q-like armorer just a few scenes earlier. Fury is nearly killed, but manages to spot the opening in the robot's head. He takes an exploding ring off his finger, and tosses it into the slot just as it goes off. The robot is destroyed, and Fury lives another day.
In the second one, it was for sure a Daredevil comic. If I recall correctly, the Black Widow was Daredevil's girlfriend at the time (which again, I think would be 70's era), and I think she helps in the fight. I don't recall how the battle was resolved, but I am sure it is the same bad guy robot, using the same attacks (radiation, etc.).
That's about all I can remember. Ring any bells with anyone?