Shadows are the main enemy in the game. They are commonly found through out the game. If Randall is seen by them they will relentlessly chase Randall with little concern for their own health as they'll run off ledges and fall to their deaths. They are infected with a virus which the government has said was a form of rabies. First signs of Shadows started in Europe, it was shortly quarantined, however it managed to find its way to the states and then finally to Canada.
They can be killed by the player if they destroy their heads or limbs. They are quite tough to kill if you don't have a firearm. If the Shadows swarm the player, it can lead to a cheap death as after the player struggles out of a Shadow's grip, he will be hurt by the attack of another Shadow.