Probably squirrels. When they are on my roof, I hear them running around. It sounds like they are in the attic, but they are actually on the roof. You need to make sure they are not in your attic. They can do a lot of damage. Search "squirrel damage to house" and look at the pics.

Get a live trap and put bread with peanut butter in it. Usually it is squirrels or chipmunks.

Probably the grudge!!

Why don't you go up there and look!!?? Set a camera up if you must. Can you see any droppings? Etc etc

everyday i hear a noise that sounds like something is walking around up there. i live in washington and i dont know what is up there i dont see opposums at all except dead on the streets, i havent seen raccoons around at all, and as of mice i havent seen those either, but squirrels i see sometimes. can anybody tell me what i should do.