This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Far Darrig (Irish)
A far darrig or fear dearg is a faerie of Irish mythology. The name far darrig is an Anglophone pronunciation of the Irish words fear dearg, meaning Red Man, as the far darrig is said to wear a red coat and cap. They are also sometimes known as Rat Boys as they are said to be rather fat, have dark, hairy skin, long snouts and skinny tails.
The far darrig is classified as a solitary fairy along with the leprechaun and the clurichaun. They are are "most sluttish, slouching, jeering, mischievous phantoms". The far darrig in particular is described as one who "busies himself with practical joking, especially with gruesome joking". One example of this is replacing babies with changelings. They are also said to have some connection to nightmares.