Mixamo Import Retarget messes character head.
I had a similar issue with my character's foot and this was because my bone was not selected in the correct bone.
This could be the reason why your head is like that as well, but it seem like it's more to do with the neck.
Check your bones configuration of the Head and Neck and see where they are placed.
answered Apr 30 '17 at 02:03 PM
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