Korean legends characterise a variety of mythical creatures, ghosts, monsters, and dragons. Many are derived from Chinese legends, but with their own unique Korean spin.
The dokkaebi is a mischievous creature, fond of practical jokes and games, but also known for rewarding good people. They are generally considered harmless, and have a penchant for challenging others to ssireum (a Korean style of wrestling). If you ever find yourself in a match with a dokkaebi, remember never to push them from the left side, only from the right. According to some stories, they are easily beaten by hooking their leg, as they only have one of those.
Dokkaebi are endowed with a few magical items. The gamtu (감투), or hat, grants them invisibility. Their club, called a bangmangi (방망이), allows them to summon any item they want. However, it cannot create the item out of thin air, thus obeying the Laws of Thermodynamics like a good little magic item; instead, the item is stolen from others. So, not much different from any other club at the hands of a robber
The haechi originally was an animal, sort of a hybrid between a lion and a watchdog, with a horn in the center of its head. Often symbolising justice, it was a common decoration of old Chinese and Joseon architecture.
During the construction of Gyeongbok Palace, geomancers predicted that the “yang” energy from Gwanak Mountain across the river would bring disaster to the nation, so the haechi statues were built to cancel out this bad mojo.
A gumiho is said to be a fox that has lived 1000 years, after which it gains the power of shapeshifting. They most often choose to transform into the form of a beautiful girl, and are rumoured to seduce men for the ultimate goal of eating their livers, or in some stories hearts. Although, it should be pointed out, in My Girlfriend is a Nine-Tailed Fox this is revealed to be a rumour that ruined the main character’s reputation and kept her from landing a husband. Of course, she was still encouraged to drink blood, and told that her boyfriend must die after 100 days.
The Chollima is one of the more straightforward creations of Korean legend, as it can be very easily likened to the Greek Pegasus. The name means “1000-ri horse,” with “ri” representing a traditional unit of measuring distance. Due to conflicting definitions, the ri is either 393 meters or 2927 meters, the latter which was adopted by Korea during the Japanese imperial era, so I’m going to guess they’re referring to the first one. Thus, the Chollima could travel 393 kilometers in a single day, which is approximately the north-south length of the entire Korean peninsula.