The Sherlock Holmes star is to take part in the Harry Potter prequel by reprising the part vacated by Richard Harris and Michael Gambon.
With the passing of the original Hogwarts Master Richard Harris passing away in 2002, McKellen opened up about the part that would eventually go to Michael Gambon.
On the back of a strong marketing campaign and lead up, the Harry Potter spinoff has started strong out of the gate as the fantasy adventure film collects big.
The Englishman knows what he has got himself in for with Fantastic Beasts, explaining that he is ready to stay in the franchise for the long haul.
As if Harry Potter fans needed any more encouragement to see this movie...
It turns out that Vernon Dursley has some backstory with James, causing him to dislike Harry for the same reasons Snape did.
J.K. Rowling let the (big) detail slip during her Fantastic Beasts Live event that was streamed across the globe.
James Newton Howard throws a big nod back to John Williams in the film's main theme, all before making it his own.
The series created by J.K. Rowling will get a reboot of sorts as the entire franchise is put back on the back screen for a limited time.
IMAX has announced the re-release of all eight Harry Potter films for one week only in preparation for the next Rowling installment.