31 Days of Monsters: The Sluagh

The Sluagh are the restless dead of Scottish legend. Welcome neither in heaven or Hell, the Sluagh have also been rejected by the earth itself, and cannot remain in their graves. They wander aimlessly through the night spreading fear, and sickness. To hear them wail in the night is a death omen.

31 Days of Monsters 2014: Draugr

A Draugr is a revenant from Norse mythology. A person who dies in a sitting or standing position — which indicates their hesitancy to pass into the afterlife — will usually become a Draugr after death. Greedy people who want to watch over their gold, or feel the need to exact revenge on others will also become a Draugr after death. 

Draugar (the plural form) usually watch over their own burial site, usually because the ancient Norsemen were buried with treasure. They can become small or large as needs be, and are immensely heavy. Most normal weapons have no effect on them, but they can be immobilized by driving pins into their feet, and iron weapons can do enough damage to them to allow their body to be burned. 

Draugar are magical creatures that can see the future and enter the dreams of mortals. Draugar like to crush their victims or drive them mad with fear. Draugar are known to kill herds of animals by chasing them to exhaustion.

Although many people become Draugr out of greed or hatred, most Draugar grow to hate their undead condition, and eventually allow heroes to slay them and claim their treasure.

31 Days of Monsters: Day Twenty-nine — Zombie (Modern)

The modern zombie is a person who has returned from the dead to feast on the flesh of the living.
It's my belief that the modern zombie is a response to the over-romanticizing of the more tradition undead monster, the vampire.
In previous generations the vampire symbolized the fear of death, disease and the fear of being eaten by predators. In early vampire folklore, they were little more than corpses who rose from the grave nightly and fed on the blood of their family members.
In later fiction however, vampires were turned into seductive, romantic figures, more akin to Satan himself tempting victims with promises of sex, immortality, power and wealth.
Whether George Romero realized it when he created "Night of the Living Dead," I believe he was giving us back a monster that deep down, we may need as a fundamental part of our psyche. Something that lets us face our fears of mortality, and bash it in the head.