How can I render an actor after post process?

I want an actor in the scene not affected by post effects, such as toon mapping, eye adaption, etc. Is there anyway to do this?

Due to the nature of deferred rendering it is not possible, but you can make a workaround, using custom depth. Take a look here.

It is quite possible, and using mask (as You’ve mentioned “custom depth”) is the solution.
But You have to forget about native Post effects like eye adaptation, or compensate them.