Role play is the next fetish. I was a bit surprised this came up as a fetish...but I guess some people enjoy sex with role play all the time. I always think of it as a bit of fun, a one off thing, but there are people who get off on particular role play.
The most popular role plays from what I could see on the internet searches are:
There can be more specific role play where age or gender may come into focus. Or even your human-ness.
Role play can be a mental thing only, or can involve dressing up and 'becoming' the character. It can occur in home, or in public. It can be for a short or a long period of time. It can cross over into your day-to-day life, or remain a short term prospect only while enjoying sex.
It can take almost any role at all :)
I think role play gets covered by many of the topics to be discussed, so I won't dwell on it here. Role play can be a very important aspect of a sexual relationship.