Basilisk is a void dragon living inside the void space
a space that exists between realities, dimentions and realms like the oceon exists between continents
he as existed before though and words
his true form is beyond plannetary size and has doomed countless worlds as easily as you would accently kill an insect
he used to live in a specific realm but was banished due to he couldnt see the value of liveforms that couldnt live on his level
because of his banishment his true form cannot enter any realities, dimentions or realms
so instead when he needs to he constructs an avatar inside the realm inquestion.
he was named basilisk to warn others and out of a sense of irony
you see basilisks are know for their ability to kill with eye contact meaning that if you earn a basilisk's attention you're already dead
however with the void dragon it's quite the oppersite because he has a tendancy to kill what he doesnt see or notice simply because he is so big
even in void space when a traveler has gone missing or is never heard from again it is assumed that Basilisk as killed them