Talk:Knight/@comment-32330498-20180528014306

''"The Steam Trading Card refers to The Knight as "Hollow Knight," though this is most likely only to avoid spoiling the identity of the true Hollow Knight." ''

Technically this is not true, it may not be called the "Hollow Knight" by users but it really is "hollow" as it is one of the few Vessels that were truely unemotional, whereas the Hollow Knight  is seen looking back in the Abyss flashback, this being a sign of regret, and in the Path of Pain flashback the Hollow Knight is again showing emotion, this time it being love towards his father, The Pale King.

This, at least, is my view of the naming here.