Real-life BSU/BAU legends - John Douglas, Roy Hazelwood, Rob Ressler (I find it interesting that he genuinely liked Dahmer), etc. I think Gideon and Rossi were created as a nod to these guys.

I don't see any question about it; for example, the scene with Hotch, Reid, and Chester Hardwicke in "Damaged" was directly inspired by Ressler's prison encounter with serial killer Ed Kemper.