First I would like to say something about the list, we all have to assume this is the only list, as we all known Bruno Heller already confirmed it. We have to let go our thoughts (me included) about the characters that we believed were Red John and they were not… Well, I will try to remove some of the suspects: Let s see when they appeared:  
-Bret Stiles (Malcown McDowell): Appeared in 4 episodes: (2x20) (3x3) (4x16) (5x8)  
-Gale Bertram (Michael Gaston): Appeared in 12 episodes. (3x1) (3x4) (3x13) (3x16) (3x23) (3x24) (4x1) (4x2) (5x1) (5x3) (5x14) (5x16)  
-Raymond Haffner (Reed Diamond): Appeared in 2 episodes. (4x 2) (5x13)   
-Reede Smith (Drew Powell): Appeared in 1 episode. (5x1)   
-Bob Kirkland (Kevin Corrigan): Appeared in 6 episodes. (5x5) (5x7) (5x8) (5x16) (5x18) (5x19)    -Sheriff Thomas McAllister (Xander Berkeley): Appeared in 1 episode. (1x2)  
-Brett Partridge (Jack Plotnick): Appeared in 4 episodes. (1x1) (2x23) (5x15) (5x22)  
 “Red John has been visible in prior episodes” (after season 3) 
OUT KIRKLAND, SMITH AND HAFFNER. 
Plus, Jimmy Gadd, one of the Lead Editors on The Mentalist, said on Twitter “Kirkland is A GOOD GUY” (I will try to put the photo in the Argue) 

SO BRETT PARTRIDGE, SHERIFF THOMAS MCALLISTER, GALE BERTRAM AND BRET STiLES
We saw a list of everyone Jane has ever met and shaken hands with. Jane simply named every single person he’s met and shook hands with, and we saw just one page of many in his little book. What we can see there is that Jane makes the list with all the persons he shook hands AFTER Red John killed his wife and daughter. So, it is not a person from his past. Well, and the big question is how Red John knows about Jane's happy memory from his childhood? Jane doesn’t t believe in psychics, here is the conversation between Jane and Van Pelt when they first met: 
Grace: Mr. Jane, I have a question regarding your previous career path.
Jane: Fire away.
Grace: When you met with other psychics, real psychics, could they tell you were just pretending? 
Jane: There's no such thing as real psychics.
Grace: I beg to differ. My cousin Yolanda is a psychic. 
Jane: Your cousin is deluded or dishonest or both.  

Jane says what Red John did was a trick, and Jane knows about tricks, he does those tricks all the time, in almost every episode. The difference for us is that sometimes Jane explains how he does those tricks, and now we don t have the explanation, so it looks like Red John is God.
In episode 1x18 Jane says: 
Jane: Hypnosis is just a way to connect to the imagination rather than the conscious mind. The mind will accept whatever the imagination creates, however bizarre.  

According to the description of Rosalind ("just under 6 feet tall”,“short straight hair”) 
MCALLISTER AND BERTRAM ARE OUT . SO WE HAVE BRETT PARTRIDGE AND BRET STiLES.
If it s true that “a kid” painted Red John face in Ellison Farm (we can argue which are the parameters of age to say that someone is a kid) it fits best BRETT PARTRIDGE. 

I WOULD NOT BE DISAPPOINTED IF BRETT PARTRIDGE IS RED JOHN, I WOULD BE DISAPPOINTED IF THE CLUES (INTERVIEWS, WRITERS, TWITTER, ETC) ARE NOT TRUE!!!!!!!!!

The FBI friends of red john - for me that places him to be a woman in the FBI. One who we have seen.

Patrick knows its her by now, he made his big reasoning map as a ploy - then left it in place (he didn't need a map because he would have done it all in his head). Then he left the matchstick, he knows that the FBI agent Kirkland and his people came in and saw his big map.
Red John got information from Kirkland so he could be all "look how amazing" and say the 7 names. Its really more like an 8th name was left out so that Patrick can lull Red John into a false sense of security - which is why he is going to go on a killing spree. Red John thinks he/she has won now, and wants to end it because Patrick keeps busting his friends.
This is a bigger plot structure than the usual inner-episode structure, but its the same. Patrick uses long con to bring the killer closer or out into the open. I have seen every episode and i usually have it figured out by about half way - but thats why i like this show because its got lots of twists. The writer hasn't left that many clues because they just want to make up whatever they feel like for the last episodes.

I am happy it is coming to a close. Even though the mentalist has brilliance its pretty normal formula - the main characters aren't going to turn out to be the twisted Red John themselves - thats too poxy.

Guys my opinion os that Red John is Patrick's father...
He is the only one who could know Patrick's every movement.....

As everyone seems to be discussing how RJ knows about PJ's memories, specifically his happy memory of that girl from his childhood, may I offer a theory?

Kirkland has been following PJ's movements since the beginning and was aware that PJ was in a mental institution prior to entering the CBI.  As he seems to be able to access any information he wishes, isn't it possible that pycho-analysis sessions at the insitutition could hold record of PJ's past including memories and inner-most thoughts?  This information could then be readily passed along to RJ.
I believe that Kirkland is, at minimum, an associate of RJ, but I feel his on-screen actions make him "too-likely" to be RJ himself.

As for the wrist-brace on Lisbon:
IMO, she made some attempt (to be shown perhaps next season) to get into PJ's room to see his progress.  I feel she truly loves PJ but does not yet fully trust him.  I think PJ noticed the potential break-in, hence his expression when she says she tripped.

I think even Bruno Heller and the production don't know who Red John is yet. That's all folks!

  I think that the list of 7 names that janes came with is something RJ could have reached to using the information brought to him by Kirkland  and his mind ... but I also think that pj knew that rj will send some one to know what he knows who in  this case is
Bob Kirkland and thats why he displayed the information that he wants rj to find leading him to the 7 names list >>> and I also think that the way rj found out about pj happy memory is from hypnotising
Lorelei Martins before kiling her (because she was close to pj and he might told her things about himself) ... so my Conclusion is that the identity of rj is not among the 7 names in the list but pj has another list that rj never reached to and he wont and the reason he was mad in the Message
Lorelei Martins read was that he sensed that pj manipulating him and he is close to find him or it is because there are some of his helpers in the list .

As many people have already done I would like to put in my two cents about each of the final seven suspects.  This is mainly because Bruno Heller has stated categorically that Patrick Jane is NOT Red John (something I have waited for, for a long time) and because he stated that one of the seven final suspects is indeed Red John {see: http://insidetv.ew.com/2013/05/06/mentalist-finale-season-6-red-john-list/} (putting paid to my [and others] immediate theory that Jane's suspect list was a fake to throw off Red John)

Bret Stiles

Head of Visualize.  Previous inside knowledge of Red John.  Likely killed, or arranged the killing of, the former leader of Visualize and the Sheriff who investigated his death.  Helped Jane break Lorelei Martins out of prison.

I think that Stiles is a strong candidate due to his position at Visualize.  This fits in with the concept of hypnosis or entrancement that has seemed to be a feature surrounding Red John's accomplices (in that they are all fanatically devoted to him and many are willing to die to protect him/his identity [see Strawberries and Cream when the assassin committs suicide])

Gale Bertram

Bertram was my main pick for being Red John's accomplice in the Season 3 finale and I was immensely disappointed when it turned out to be O'Loughlin (except for the fact that he died as the Craig/Grace storyline was extremely annoying to me)

Director of CBI.  Previously a Red John Mole suspect. Talked about how he "gutted" someone at poker (as a professional poker player myself this is not standard poker terminology) and seems consistent with Red John's MO.

Another reason for my suspecting Bertram was the possibility that Red John knew that the Pacific Palms Hotel sting operation in Strawberries and Cream was a trap.  Timothy Carter (Posing as Red John) said to Jane "when O'Loughlin told me of your little TRAP I was so pleased.  One more chance to teach you a final lesson in humility"  To me it is significant that Carter said "trap" instead of something like plan, or scheme.  It suggests inside knowledge to me as the only other explanation I can think of is lazy script writing.  Therefore I thought Bertram was a good candidate from (from Season 4 onwards) to be Red John or another of his accomplices.

Overall I think Bertram is another good possibility as his position as Head of the CBI (and likely other high ranking law-enforcement positions) underline a theme about Red John that has been present since almost the beginning of the series.  Also, something I didn't mention above was that he quoted a line from "The Cradle Song" by William Blake who Red John himself quoted in the Season 2 finale.

Raymond Haffner

Supervising CBI Agent.  Left/leaving for Private Sector (asked Lisbon to join him and mentioned it was for much more money)  Member of Visualize. Possible connection to 1988 Red John killings at Elliston Farm.

Despite having only two episode appearances Haffner also seems to be another strong candidate (though not one I want to be correct).  As a member of Visualize and an important person in the CBI (and probably the wider community also) he would likely have a good personal relationship with Bret Stiles which could explain where Stiles is getting his inside information on Red John.

His possible connection to Elliston Farm fits around his approximate age and the age at which he said he joined Visualize (around 17 or so if I remember correctly).  Also the fact that he asked Lisbon to join him in the Private Security business is consistent with Red John's attempts to destroy everything Patrick loves and holds dear.

Overall ANOTHER strong candidate (this detective malarkey is pretty hard!) that seems to fit many of the criteria that have become common knowledge to most regular viewers.

Reede Smith

FBI Agent, partner of Gabe Mancini.  Only appeared in the Season 5 premiere which was shortly after the failed Las Vegas sting operation.  Apart from the law enforcement connection, the timing of Smith's appearance on the show is the only real [intangible] evidence pointing to it being him.  It could be that Red John was trying to observe Patrick directly (something he clearly enjoys doing based on previous actions) and find out if the events in Las Vegas had left him any closer to finding him (Red John) also, was I the only one who thought Smith looked faintly amused by the whole "Red Bead Incident" in 5x01, which would make a certain amount of sense if he was in fact Red John.

Overall, not much to go on, a lot of conjecture and no real evidence or connections.  I hope he is merely a red herring as having only two/three suspects to look into would be perhaps too easy!

Bob Kirkland

Agent with the Department of Homeland Security.  He has engineered it so that he has been kept apprised of the Red John case for over five years (see "Red Dawn" Limo Scene at the end of the episode)  Killed Jason Lennon (Red John accomplice who likely had key information about Red John)  Had Homeland Security Agents break into Jane's loft and copy his Red John "project board" and made his own version of it.

Kirkland is the only person on this list I personally believe is definitely NOT Red John.  This is because before he killed Jason Lennon he asked him [Lennon] if he knew who he [Kirkland] was ad Lennon said that he didn't.  Lennon likely knew at the very least what Red John looks like as he delivered Lorelei's sister to him.

I believe that Kirkland is either a high-level Red John accomplice/protege/partner or that he is himself hunting Red John in the same that Patrick is.

Sheriff Thomas McAllister

Only appears in 1x02 "Red Hair and Silver Tape".  He seemed interested in Jane's "psychic" powers and lost at Paper/Rock/Scissors every time when he played against Jane.

McAllister has the law enforcement connection that seems to be highly relevant but as he only appeared in one episode I believe he is likely to be another red herring.

Brett Partridge

Last but not least....

Partridge has been a suspect of many fan theories since most probably the first episode and as a results much has already been said.

He is the epitome of the "Creepy Forensics Guy" persona.  He has worked Red John cases (copycat  and genuine) He quotes classic literature like Moby Dick and Charles Dickens like Red John with William Blake.  He appears to have a strong dislike of Patrick Jane (although this seems to have mollified in 5x22) and he also appears to revere Red John as seen in 1x01 and the Season 2 finale.

He has some voice similarities to Red John's voice in the Season 2 finale.

The William Blake painting "A Brace of Partridge" could have been the inspiration for Red John to take the name "Brett Partridge as an alias.

Overall I think that Partridge is another strong contender, he seems to fit the thoroughly macabre nature of Red John (noted by Patrick Jane in his first list of suspects) and his [likely high-level] position in the CBI forensics team would give him huge access to the CBI archives, computer databases and evidence rooms.  The William Blake and other literature connections (not just through Partridge) throughout the series seem to me to be too frequent to be random and are there for a reason (whether as red herrings or otherwise) and he seems to fit Rosalind Harker's description of Roy Tagliaferro perfectly.

Well, that is my two cents on each of the final seven suspects and as Bruno Heller has confirmed that Red John is indeed one of them we are certainly in for a roller-coaster of a season when September comes around!

Please comment and let me know your thoughts and whether I have got any information wrong and link me to your theories as well please!

Happy Hunting!

Pyrites.