Chaser

The Chaser is the most common type of Mare, given that being chased by monsters is one of the most common nightmare scenarios. A Chaser's main goal is to hunt you down and catch you. It's a simple beast, but a popular one nonetheless.

Behavior
The intentions of a Chaser in regards to what it will do if it catches you can vary. It can attack, eat or kill you, but more often then not the Chaser won't catch you at all, but rather torment you with a constant threat of capture. Although its approach is simple in nature, there's more tricks up its sleeve than merely running towards dreamers. On top of an almost unfairly keen ability to locate your hiding places and wait in rooms ahead of you, it can also cause you to have an extremely hard time running away fast enough. This phenomenon is extremely common, often described as slow-motion running or the feeling of wading through molasses. Despite the terrible feeling of hopelessness caused by this phenomenon, it doesn't often actually lead to the Chaser catching you, and may just be a demoralizing facade. Attempting to hide most often ends in a scene of the Chaser slowly finding your hiding place and ending the dream.

Trivia

 * Being chased by something is the second most common nightmare of all time.