Custom entities?

[The Shanus]

Hey i was working on a custom story called Ender and well its called this for it takes place in endersburg Scotland and revolves around the slender man however i have been using entities that...aren't exactly mine i love custom story's that use custom entities for i usually see them as a resource. i never really release my custom story's for this reason and i usually keep them for just me and my friends but am i "allowed" to release them with these entities freely or do i need permission from the creators?

You need permission from the creators

Thank you

If you know who they are, simply pm them, most just want their names in the credits.