Most hikers can safely enjoy their time in nature without worrying about attacks from anything more vicious than the blood hungry mosquito. The famous naturalist and former backcountry ranger Edward Abbey once said that the Wilderness can be defined "as a place where humans enjoy the opportunity of being attacked by a wild animal". While this is true it still is wise to be aware of the potential dangers of the environments you hike... because ignorance is not always bliss. By being conscious of what threats certain wild animals can pose, and by knowing how to properly react to those threats, you will greatly improve your chances to sucessfully survive an animal encounter.
There are some animals that hikers normally watch out for on the trail. Bears are usually on the top of most lists but there are some animals that most wouldn't expect to have the ability to kill or seriously injure people.
Wild pigs are a growing threat. They can exhibit territorial behavior and can quickly attack hikers.
Moose are fast chargers and walking with dogs can provoke an attack.
Mountain lion populations are increasing and they are moving back into areas they had once originally roamed decades ago. Mountain lions (cougars) have been known to prey upon humans.
Some parts of the country have snakes that can inject us with deadly venom.
Wolf attacks are rare but the danger still exists.
Coyotes have been known to attack small pets and children.
Where the trail passes thru areas where humans live feral dogs are a risk.
Ticks put us at risk for lyme disease, etc.
There have been a few reported raccoon attacks that happened on the trail. Also raccoons are good at stealing your food.
It is safest to always keep your distance from any wild animals, especially if they are acting strangely. Animals in the wild can be unpredictable. Additionally wild animals can be carriers of rabies... especially raccoons, bats, skunks, foxes, and coyotes.