Ceridwen

Ceridwen is - again - the First Goddess, this time in her aspect of wise old woman.
Or, if you like, of witch.

Sure enough, Ceridwen owns the archetypical witches' cauldron, in which strange ingredients are simmering a year and a day.
In a variant of the earlier mentioned story of Finn, it is the dwarf Gwyon Bach who licks up the three drops that bring knowledge.

Afterwards, he has to flee the wrath of Ceridwen through a succession of metamorphoses.

Wrath? Or was it intended that Gwyon Bach sucked up those drops?
Who knows the hidden agenda of a (omniscient) Goddess?
Fact is (if you could call it a fact...) the dwarf first changes himself in a hare, and is then chased by Ceridwen the greyhound.
Gwyon becomes a fish, only to see himself pursued by Ceridwen in the form of an otter; Gwyon manages to fly away as a bird, Ceridwen changes into a faucon. Gwyon then tries to hide as a grain of wheat, but is eaten by Ceridwen the hen.

Thus, Ceridwen becomes pregnant (obviously, Gwyon Bach had yet another metamorphosis up his sleeve), and finally gives birth to Taliesin, the mythical Welsh bard.