There are various instances of a “trinity” in Harry Potter, such as the Harry-Hermione-Ron trio, and the Peverell brothers who each owned one magical artefact of the Deathly Hallows.
Oh and there’s the Triwizard Tournament between Hogwarts School (of Witchcraft and Wizardry), Durmstrang Institute, and Beauxbatons Academy (of Magic).
I’ve heard of this fan theory that suggests that Voldemort represents the Elder Wand, Severus Snape the Resurrection Stone, and Harry Potter the Cloak of Invisibility. Not to mention that all 3 of them were Half-bloods.
And now, I’ve suddenly realised that 3 types magical creatures in the Harry Potter Universe, could correspond to the 3 magical artefacts that make up the Deathly Hallows.
These three types of magic creatures, which are not symbols of any of the 4 Houses of Hogwarts, are prominent even in the muggle world of mythology and folklore: The dragon, the Unicorn, and the Phoenix.
The Dragon could be associated with the Elder Wand, in that it’s powerful, deadly and even fatal. Both make good prizes that every wizard would want to possess.
The Unicorn, shares an similarity with the Resurrection Stone which was set in the Peverell ring passed down generations in the Gaunt family (Voldemort’s maternal ancestors). The Resurrection Stone could (supposedly, according to The Tale of the Three Brothers) bring back the dead to life. Similarly, Voldemort survived on drinking unicorn blood with the help of Quirinus Quirrell in the Philosopher’s Stone (Book 1), tethering to life the Dark Lord who has lost form after his body was destroyed when he first tried to kill the infant Harry Potter at Godric’s Hollow.
The Phoenix, the immortal magical creature, bursts into flames when it’s growing too old, and rises from its ashes. This aspect is particularly similar to the Cloak of Invisibility, first owned by Ignotus Peverell, the cloak that supposedly enabled him to hide from Death until old age as depicted in The Tale of Three Brothers. Another characteristic of the Phoenix is the potent healing powers of its tears, which as seen in the Chamber of Secrets (Book 2), was the antidote to Basilisk venom. Thus the phoenix (in this case, Dumbledore’s phoenix Fawkes) is able to save lives and thus allowing Harry to live longer, a function which I believe to be similar to the Cloak of Invisibility.
Last but not least, these three types of magical creatures, the Dragon, the Unicorn, and the Phoenix, provide the most commonly-found wand cores, namely, dragon heartstring, unicorn hair, and phoenix feather.
“Draco dormiens nunquam titillandus.”