He is many. Specifically an organized group with one true killer/mastermind and dozens of other followers and pawns willing to kill and die for him. If red john has to be one of the 7 suspects I'll go with bertram; however, kirkland, stiles, partridge, haffner, and minelli are his friends and main accomplices. Here's the evidence:

1. The actor playing Bertram was born in 1962. He'd be 26-27 in 1988, the possible first Red john murder. Most serial killers commit their first murder at an average age of 25-27. The timeline fits perfectly. Could easily be involved with visualize and stiles and haffner at this point.

2. Bertram is manipulative and deals with media at the CBI. Note that red john is very concerned with his image in the media and how he's portrayed. Just like Bertram.

3. Bertram might fish with minelli and could have met Jason Lennon while fishing as well. Explains their friendship and connection. We also don't know about Bertram's past or life like we do the other agents at CBI.

4. Alexa Shultz worked with Bertram and seemed uncomfortable around him. Could be an act. She's also the one telling minelli about jane's stay at an insane asylum at the request of Kirkland. If minelli and Kirkland are working together and reporting to Bertram then they could easily track down Jane's therapist at the institution and hypnotize her to get Jane's memories, feelings, and mannerisms. This is how red john knows Jane's happy memories. He doesn't have special powers he's just messing with Jane and jabbing at his confidence.

5. Bertram was with Jane which is how he knew where to tell timothy carter to meet him at in the season 3 finale. Also Bertram disappeared after Jane went to confront him along with the red shirt guy. Another follower possibly.

6. When he kills he leaves no evidence. Is it because he's really good or because he has Brett partridge, who's always the first at the scene during red john crimes to come in and clean up making sure all evidence is gone by the time everybody else gets there. Remember partridge said he was working on red john murders since he started.

7. Lisbon's been acting weird lately. Like she's might be an accomplice. As a matter of fact ever since she started playing poker with Bertram and the others. You do the math. They've gotten close, Lisbon seemed worried Jane suspected bertram, and has been really prying at Jane trying to get any clues. Keep in mind red john seems to find out a lot of info about Jane's plan that only he and Lisbon were aware. I smell a rat.

This is my theory as how Bertram could be red john and how he'd pull it off with his accomplices. Let me know what you think.

Hey gu ys! What if the 'happy memory' is a fake? I mean of course he met the woman Lili but may be this is not a happy memory although by chance , randomly,someone that he met as young. So may be he invented the quote of happy memory because he already yave recorded with Lorelei the video, with the seven suspects, etc and that's the reason of the mention of the happy memory and the list. He has all planned for kidding us and Lisbon may be because he wants to protect her or may be because he suspects she is an RJ accomplice. So for any of those reasons he has made the video and invented the 'happy memory'

Red John is Brett Partridge
A lot of theory say that. I few times though Patrick jane was Red John but no... Lorelei Martin could have get him easily and so many other contradiction...

The list of the name is "guessed" by RJ? well someone spying hard on patrick could have find the list and read it... or anyone with access to the Bob "copy" of Patrick could have guessed...

But WHO the hell could know about the happy memories (from the S05E22) ??
If someone got a plausible answer, he is Really welcome ! Because i don't know how Brett could have know this (and i would really be disapointed if Brett is RJ... not a fun character/he isn't here a lot...)

Sheriff Thomas McAllister!

Introduced so early and neat. The age description on RJ fits him best. Also the height feels about right.
We got the "he is mar"(shall). We know RJ easily can access Police Uniforms.
(when he poison that whore of a secretary killing boscow)
We know he got ties and friends in law enforcement.
He is set to return in season 6. Who else could it be?

Patridge? Too obvious
Stiles? Too old too connected with both RJ AND PJ and too focused in the series
Haffner? Maybe but hes young RJ was a close friend to Dumars father.. and dumar is about the same age as Haffner.
Smith? Who's that? hes too fat.
Kirkland? To obvious i get a vigilante vibe about him, either he works solo or he will get killed by RJ.
Bertram? Faking hes superbad poker/deceptiveskills? Pulling off that inspiring speech when boscow with crew got killed?Nah.

Mcallister prolly is RJ with hes most usefull asset somewhere within the CBI core.

Ok so this is not a theory on who is RJ but more of how the hell did he do that? and my theorys on them...

The happy memory thing?... must be when PJ was in mental hospital he must have been heavily sedated at some point & can not remember telling that doctor Sophie Miller about it. Or he was hypnotised in there by someone.  Its the only way!! people can not see or read your mind thoughts.  Rj is a very clever cunning psychopathic killer yes but not superhuman. got to be simple answer.

knowing the whole 7 list thing...? this im not sure on and this is a bit of a long shot but if i had to take a guess the only way i can see how RJ knew about Janes list is PJ  only started making his name list after Lorelei told him about the hand shake, so maybe she played him and this was RJ plan all along. If PJ can make a list in that amount of time then why can't the clever evil killer do so too.  Maybe lorelei was told by RJ to tell him that information, this would explain why she out lived any of his other follwers and why she was in jail for weeks and not 6 feet under. Maybe lorelei already knew rj killed her sister or even ask him to do it and she didn't care like she pretended too with those 2 people she tortured, it was all part of game to con Jane.  Why? Rj would want Jane to know this info I don't know? but maybe RJ just wants to end the game and kill him now.

I realise that is bit much and prob not even right but RJ and Jane are so alike & clearly intelligent and we all know that jane has no life these past 10 years and so anyone he shook hands with is cbi/work related (mainly) and RJ could easily windled down the list of 7 names like PJ has & he knew jane was trying to do so too. i think RJ may have come up with the 7 names before jane did and made that video then, before killing lorelei as she had served her purpose in his game.

I'm not saying i'm right but just wanted to share and this is what i'm thinking right now after series 5 and I'm sure when series 6 is back on I'll change my views or the writers will go down a totally differ route with the list thing and i'll be totally on the wrong path i'm sure.

I think maybe it is the priest from the ''Red Barn'' Episode, I still don't think that any of the 7 is Red John except maybe Bob Kirkland.
I do however think Van pelt is working for Red John , And i did'nt for one min believe  that Lorelei was telling the truth on the cd or is in any danger , But maybe is is pregnant for Patrick <<<<<<<Now would'nt THAT be something !!!!! ;)
Patricks own father was one of my suspects but i don't know if he is still alive or not , Just a thought.

I see that people are talking about PJ's brother Jimmy. I think it was a made-up story by Jane just to mess around with Dr. Wagner. Did I miss something? I mean does anyone have a firm clue that Jimmy actually exists? This information can change everything. Can anyone tell me for sure please???