Doppelbangher noun: The porn star that most closely resembles a person.
As far as I can tell, the term originated on a subreddit that allows people to leverage the hive mind to help identify the porn star equivalents of whomever they happen to be crushing on. In my brief perusal of the thread, the majority of the requests are for friends/classmates, with some creepier ones mixed in(step mom, best friend's wife, etc…). The other fairly common desire is for the more traditional celebrity crush.
I've compiled several of the best suggestions here… For science...