This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Hircocervus (Medieval Bestiary)
The hircocervus, also known as a goat-stag, was a legendary creature imagined to be half-goat, half-stag. While the name derives from a portmanteau of the Latin 'hircus' (goat) + 'cervus' (deer), there is no proof that the species originates from a crossbreeding of goats and deer, nor even that a viable offspring of such a union is possible.
The Hircocervus is an interesting creature found throughout medieval folklore. The idea of the goat-stag goes back at least to Plato, who used it as an example of a thing that was knowable even though it didn’t exist. Its first appearance in English is in a manuscript of 1398 now in the Bodleian Library in Oxford.