Fairies or Dan-Unra are magical creatures that appear in the Hellboy series. The recurring Irish fairies that were often seen observing Hellboy were the Daoine Sidhe. There are supposedly other fairies and fairy courts in the countries in Europe.
They are not as old as the giants, and warred with them in the past.
In the novel The God Machine Hellboy encountered the fae folk known as the Graken Spriggin.
History
According to the ghost, William, during the war between the Watchers and the Ogdru Hem, three angels fell in battle and the first one was hurled into a forest. As it laid there, it said that it had been justly killed for the evil he had done, and, in an effort to make amends, it passed a bit of its spirit to the smallest and most innocent of all forest creatures. Over many moons, the creatures changed and gave rise to an entire new race of beings. The Secret People. The Forest People. The Dan-Unra or Fairies.
The Daoine Sidhe are descended from the Tuatha Dé Danann, Irish mythological beings considered gods or ancient spirits. After their defeat by the Fomorians, they retreated into parallel or underground worlds, becoming the fairies of Irish folklore.