Adult Fantasy series about a wizard whose name starts with C and the dragons turned into human-like shapes, but without faces and always wearing armour.

[Aiden]

It was collected into three large books with the third one having a bunch of short stories, with one called Skins where a teaveling group gets trapped in a castle with a monster that kills people and then steals their skins.

I read these books at around 2006-2009.

[Becca]

Not sure if you're still looking for this, but it could be the Legends of the Dragonrealm series by Richard A. Knaak. Legends of the Dragonrealm, Vol. II includes the novella 'Skins'.