Redlin5 said:
In terms of adaptations, whether be it comic or literature, those canon's are, and always should be considered, separate unless the IP owner/Author deems the extended work canon (much like how pre-Disney Star Wars EU books were canon, with the caveat that Lucas could trump the books at any given time, much to the chagrin of great writers like Karen Traviss).
But usually the adaptations should be held as an alternate universe. It does not break the canon that came before, kinda how DC and Marvel have used various versions of their comic universes as separate but equal canons. The reason I say it like this is because it's ridiculous to me that people expect a movie adaptation to follow the story exactly, especially in comics. First off, books (non-comic) are difficult to adapt to screenplays because of the way the medium is presented, and headcanon-like perspectives on how characters look may not match up with the producer/director's vision of said adaptation. Comics have a more visual aspect, but because of their serial nature, have a large volume of stories being told, not all of them have been contiguous.
And not all adaptations are successful or even good, which is honestly subjective material for the most part. LotR was visually, to me as close to the books as one could get with a few glaring deviations, but the characters somehow looked and sounded exactly as they did in my head, or close enough to it that I ended up incorporating the movie versions.
Anyway, canon is a tricky thing, but there is always a delineation between official versions and headcanon, and people are absolutely welcome to their own viewpoints but it comes down to the original author or the current IP holders to actually determine what canon is. Doesn't mean they'll always make the right choices, doesn't mean we always agree with the directions and that's why in our own subjective sphere, headcanon > official but in the larger scheme, official > headcanon. A strange dichotomy, no?