If you're writing a .dll you can prevent that dll from getting loaded into some processes by returning false from the dllmain.

I'm looking for a way to do it the other ay around. I have an exe, and I want to prevent a certain hook dll from getting loaded/injected into my exe.

A customer is running some software which loads a hook dll into our exe, and this is subsequently preventing our application from running as intended. Both our software as well as the third party app is required, and there is no way to get the third party dll changed. (no longer supported).