Forehead
Sure, this forehead is a bit square, but that's because it's Frankenstein's Monster's forehead. Also, did you notice that this is just the top part of the head (冂) radical? This is just the forehead part of that!
Don't confuse this for a roof! You know this is a forehead and not a roof because this doesn't have a cute little chimney sticking out of the top. Foreheads definitely don't have chimneys.