Every single one
The houses of Midnight started out as an idea that Z had. When Harry changed his last name to Midnight, Z got the idea to take up a last name all the workers could take up, since not everyone might feel like they could do justice to such a name.
So he took on the name Starcloak. The name was meant to represent the vast, night sky that could encompass countless stars, and was therefore meant for the masses to follow along. To a small degree, that is what happened.