The Creatures are a race of extraterrestrial monsters and are the main antagonists in A Quiet Place. They invaded Earth sometime to the events of the movie. They use their heightened sense of hearing to hunt anything that makes a sound.
Biology
They are shown to have plated armor that moved around as it was seen when one approached Evelyn and Regan. They are also shown to have extremely delicate ears as when Regan used her hearing aid to make high frequency sound waves, they are shown to squeal in pain and open their heads and expose the vulnerable skin underneath the armored plate. If the high-pitched noises got louder, they could get to the point where they temporarily collapsed from the pain. They also roar when they hear the noise.