The unicorn is a legendary animal that has been described since antiquity as a beast with a large, pointed, spiraling horn projecting from its forehead. The unicorn was depicted in ancient seals of the Indus Valley Civilization and was mentioned by the ancient Greeks in accounts of natural history by various writers, including Ctesias, Strabo, Pliny the Younger, and Aelian. The Bible also describes an animal, the re'em, which some translations have rendered with the word unicorn.
The horn is disputed be either made from bone or keratin which comes from the center of the forehead, between the eyes, but in folklore, the substance it was made of was called alicorn, and it was believed that the horn holds magical and medicinal properties. The Danish physician Ole Worm determined in 1638 that the alleged alicorns were the tusks of narwhals. Such beliefs were examined wittily and at length in 1646 by Sir Thomas Browne in his Pseudodoxia Epidemica. False alicorn powder, made from the tusks of narwhals or horns of various animals, has been sold in Europe for medicinal purposes as late as 1741.The alicorn was thought to cure many diseases and have the ability to detect poisons, and many physicians would make "cures" and sell them. Cups were made from alicorn for kings and given as a gift; these were usually made of ivory or walrus ivory. Entire horns were very precious in the Middle Ages and were often really the tusks of narwhals.
In European folklore, the unicorn is often depicted as a white horselike or goatlike animal with a long horn and cloven hooves (sometimes a goat's beard). In the Middle Ages and Renaissance, it was commonly described as an extremely wild woodland creature, a symbol of purity and grace, which could only be captured by a virgin. In the encyclopedias its horn was said to have the power to render poisoned water potable and to heal sickness. In medieval and Renaissance times, the horn of the narwhal was sometimes sold as unicorn horn because of the similar likeness. They also have silver to blue coloured blood depending on the story and are roughly the size of a shire horse-which is huge.
Unicorns are also part of the royal family's Coat of Arms of England, as it is depicted rearing next to a rampant lion, with the both of them wearing a crown. In Germany, there is a crest depicting a white unicorn on a red background, which are the arms of Schwäbisch, Gmünd. There are many other crests which depict the unicorn as it is a symbol of power.
In the film Legend, which stars Tim Curry and Tom cruise at a very young age, the myth of the unicorn is that they are always in pairs and when the horn is cut off, you can wield its magical power either in good or evil. To bring the unicorn back to life, because cutting the horn off kills the animal, you need to bury it where the unicorn fell. The magic power of a unicorn is incredibly powerful, rivaling that of a phoenix as it can undo powerful enchantments. They are very wise as they know who their enemies are, such as in the film Stardust, where the unicorn can even undo simple casts. But in the first Harry Potter film, the stupid animal got caught by He who must not be named and was essentially killed.
Similar to the unicorn is the Chinese Quilin, though I think otherwise myself.