Whether you are in a survival situation or just having a good time out there in the wilderness, you have to be aware of what are called the Widow Makers.
The term might be looked at as being sexist, since people of both genders regularly enjoy the wilderness, but for the moment, let us look at it as a generic term … like manhole, for instance. I suspect the term came into being many moons ago, when people were living the hunter/gather life and it was the man who went out hunting for food while the lady tended to the home. And of course, the subliminal assumption that all those who venture into the back country are married. It is supremely difficult to become a widow or a widower unless tied in the bond of holy matrimony! Like I said, let us look at the concept behind the term instead of dissecting the term itself.
Like the name suggests, Widow Makers are things that can kill you, turning your wife into a widow. And these are in addition to succumbing due to lack of food, lack of water, injuries, etc.
Widow Makers are natural elements, as well as living things.
For instance, if you are not careful about your shelter location, you could get crushed under a dead tree that falls on you in the middle of night, when a storm starts to blow. Or if you are sleeping in a creek bed that looked as dry as a bone and there is a flash flood, you could be swept away, trapped inside your tent. Be careful of sleeping near rock faces with loose rocks, they can slide down and even small rocks and pebbles tumbling down from above can effect a serious injury if they hit you. If you make your shelter in a place full of dense undergrowth or fallen leaves, you are right in the middle of snake and scorpion territory. Lay your shelter in as clear a floor as possible.
Other things that can kill you are plants. If you do not know a plant, do not eat it, it could be poisonous. It makes a lot of sense to take local knowledge before you head into the wilderness to be able to identify edible plants. If you have to eat plants for survival, carry out the Edibility Test.
As far as the living animal world is concerned, there are a host of creatures out there that can kill you - from large animals like elephants, rhinoceros, bears and crocodiles, to slithering reptiles and lizards, to wriggly insects, scorpions, bees, wasps, etc.