9. Michael Gambon - Albus Dumbledore (Harry Potter Series)
For a time, it felt as though there wasn't actually a soul walking the Earth who hadn't at least picked up one of J.K Rowling's Harry Potter novels for a quick skim to see what all the fuss was about.
Surprisingly, though, one of the most notable presences in the eventual big-screen adaptations of the Wizarding World actually never so much as turned a page of the source material during his time in the cloak.
Not really feeling the need to add this particular element to his preparations for the all-important role of Albus Dumbledore, Michael Gambon went on record on a number of occasions to confess that he had little desire to comb through Rowling's pages.
On top of stating that it's "safer" to just simply follow the script he is handed, the actor who stepped in for the late Richard Harris in the part would also note that if he had opted to read them, he'd likely get upset about the scenes that were missing in the screenplay.
Had Gambon actually given the books a read, however, there's a chance he would've potentially been able to dodge the odd backlash sent his way by those who felt his version of the character wasn't faithful to the one on the page, with a number of upset Potterheads feeling the Brit's take on the powerful wizard was far harsher than the one they'd spent time with in the novels.