I don't know who's RJ, but it's definitely not Bret Partridge. Everyone who thinks it is him is taking all the clues too literally. You can't trust anything of the details about height, weight, beard, hair, age, etc. since they change over time and could easily be frauded. 

Even if Red John is a group, there is still a leader to that group who is the true RJ. The 7 people list could be a white lie on the producer's part on so many levels. Maybe someone on the list is technically a RJ, but no the leader. Maybe Jane had more suspects and lied to Lisbon. 

Anyone arguing for PJ is also wrong. Multiple personality disorders do not work like that. There's no way he could keep a part of his personality away from himself and everyone else. Obviously the childhood memory is extracted from a relative of Jane's; there's no mindreading or hypnosis involved for that either.

I think Red John is Alex Jane, Patrick's father. He teached so much trick to Patrick and he has too many information about him. I don't want to see a Luke Skywalker scene but it makes sense.

I just read Theory #3123. The author speaks about the ring Red John is wearing on his left hand. Betram is the only one wearing a ring. It was like a revelation to me. Red John is not a single person. I think this Red John who is wearing a ring is Bertram but I don't think that Bertram is the only Red John. There are many Red Johns. 
It seems possible for all the seven people on the list to be Red John (or maybe just some of them).
I think Red John is like the demon from the Bible; when Jesus asked him his name, he replied: "My name is legion for we are many". 
I think Red John is not a person, but a title, a distinction. And I will go further and say that the Red John's accomplices who got caught are people who didn't pass the initiation test for becoming a red john.
(I have to mention that the religious analogy is just for the analogy's sake)

There have been lots of mentions of those involved in the show saying maybe we had already met RJ after season 3 and/or others. It is entirely possible that this was said back then because they hadn't even decided who RJ was at the time. And perhaps they still haven't decided who RJ will turn out to be - either because they just haven't or don't want to make the decision until next season to keep it secret or because they are going to seek some viewer input. CBS did make history earlier this year on Hawaii Five-0 by having three alternate endings based on the three suspects and letting the viewers vote during the commercial break.

I think Red John is the mother in How i met your mother. 

The list from the Season 5 Finale is legit.

http://insidetv.ew.com/2013/05/06/mentalist-finale-season-6-red-john-list/

I am the only one who thinks Robert Kirkland is a 'good' character?  I think he is also pursuing red john like Patrick Jane.