Shelter

clothes for inclement weather (depending on conditions those clothes are either on your body or in your pack)

an additional extra insulating layer of clothing (your sit-down-for-lunch layer)

firemaking kit

knife

some cordage

some means for procuring and cleaning water (If you choose boiling then you also have WARM drinks, which is a huge plus in cold climates).

paper map plus compass (and the skills to use them). If you use a GPS then bring paper map and compass as backup.

Food (not nescessarily 3 day rations - think one more meal than you need for the planned trip plus some snacks.).

Bare-bones minimum 1st aid kit.

Signalling (which may include some or all of the following: PLB, cell phone, whistle, fire, signalling mirror, bright colored clothing/bivy bag)

EDIT: LED light.

I'd also wrap a couple of feet of gorilla tape (or duct tape) around some items. VERY versatile.


Now exactly how heavy you go on each of the above items is highly dependent on climate, season and how rugged and remote everything is.