Here is a list of mythical creatures beginning with this letter and I am constantly gathering information from each continent and continually updating.
Afanc (Welsh)
The Afanc, sometimes also called Addanc, is a lake monster from Welsh mythology. Its exact description varies; it is described variously as resembling a crocodile, beaver or dwarf-like creature, or a platypus and is sometimes said to be a demon. The lake in which it dwells also varies; it is variously said to live in Llyn Llion, Llyn Barfog, near Brynberian Bridge or in Llyn yr Afanc, a lake near Betws-y-coed that was named after the creature.
One of the earliest descriptions of it is given by the 15th-century poet Lewys Glyn Cothi, who described it as living in Llyn Syfaddon, in Powys. One tale relates that it was rendered helpless by a maiden who let it sleep upon her lap; while it slept, the maiden's fellow villagers bound the creature in chains. The creature was awakened and made furious; its enraged thrashings crushed the maiden, in whose lap it still lay. It was finally dragged away to the lake Cwm Ffynnon, or killed by Peredur (Percival, Peredur's name in Chrétien de Troyes' telling of the Arthurian cycle).