Suspect: Patrick Jane's father (played by Nick Chinlund)

Reasons:

He is the only one who could know that Eileen was a childhood memory for Patrick (this to me is the most critical clue)
He was a conman who taught Patrick how to think like one, and can thus get into his mind
He may have hated Patrick for abandoning him and would resent his new family enough to deprive him. Also, explains RJ's obsession with Patrick


Against:

Not on the list- but the list could be a red herring despite Heller's insistence (similar to Brad Whitfield masquerading as RJ)
Too old- would be in his 60s (but so is Stiles)

Lets look into the 7 suspects in more detail:

1) Brett Stiles has many charasteristics to be Red John. He is manipulative, powerful, wealthy and very intellgient. He runs his own cult and has a lot of followers. However, I would think he is too old to be considered a "kid" in ellison farm in 1988. Besides, i would not think that the head of Visualize would be working there anyway. Physically, I do not think he is strong enough to "overpower his victims" as Red John does.For me, his role in helping Lorelei Martins escape convinced me that he is NOT red john. Lorelei could have so easily reveild much more about RJ and possibly even his identity, especially when Lennon was shot. I would not think Red John would have taken that risk to expose himself.

2) Reed Diamond has been antagonistic towards Jane but does not match the physical description of RJ at all nor does he have the power and influence to be a flawless  serial killer. The fact that he and Gabe Mancini failed to solve the hotel case in the season 5 episode 1 suggests that he does not have the intellect either.

3) Sheriff Hardy again would not be a "kid" during the Ellison farm incident, he is simply too old and was beaten several times in rock paper scissors by jane which RJ would not allow to happen. His failure to solve the case in Red Hair and Silver Tape suggests that he does not have the mental capacity to be RJ.

4) Ray Haffner is a high ranking member of the CBI and seems to be reasonably smart. He was also  a member of Visualize. However, he was easily misled in the season 4 episode 1 (I think the episode about the fitness center) which RJ would not allow to happen. Also, RJ would also not have accidently revealed that he was a member of Visualize as Ray Haffner did, remember, the show has told us that RJ does NOT make any mistakes.

5) Gale Bertrand is the head of the CBI and hence does have a lot of power and influence as Red John would. He is also spoken about John Blake's poem that RJ also did in the season 2 finale. He also does not like Jane.However,  Gale Bertrand would not ask Jane's help in poker if he was Rj. RJ is just to egotistic and full of himself. He also does not match the physical description of RJ that Rosalind Harker told us since he is too fat, bald and probably too tall as well. Also, Gale was one of the suspects in season 3 to have murdered todd Johnson. If Gale was RJ, then he would have murdered Todd Johnson himself since he was very close to the holding cell and not had Craig O Laughlin do it.

6) Brett Partridge is also antagonistic towards jane and frequently insults psychics. He also only appears in RJ episodes and has a high voice. Also, the person who murdered Rebecca also seemed to be wearing a forensics jacket.However, I think that he does not have the power and influence to be RJ as he is only a forensics guy. Jane frequently insults him which RJ would not tolerate at all. Brett also mistakenly identified a copycat to be the real RJ which the real RJ would not have done ("I'll show you clever" part). Also, in the season 5 finale, RJ is suggested to be psychic himself by stealing a happy memory from Jane hence this would contradict Brett's behavior.

7) Finally, Bob Kirkland is a mysterious one to me. his interest in finding Lorelei Martins and RJ despite the fact that he is in Homeland Security is very weird to me. His murder of Jason Lennon suggested that he is a RJ disciple or RJ himself but I am not sure. People have suggested that he was Miranda Martins boyfriend which could very well be true. Also, RJ had the list of the 7 suspects while Lorelei was still alive but the Homeland Security broke into Jane's place after she was dead hence there is an inconsistency. We found our that he was working with Alexa Schutlz in order to get period updates on the RJ files from Virgil Minelli. However, I think RJ would just use an accomplice to get those files for him from the CBI.

One thing that puzzled me in the season 5 finale was how did RJ know the names of the suspects? How would RJ know the names of all the people that Jane has shaken hands with? I am suspecting that RJ has another insider in the CBI who is feeding him information like Gale Bertrand or someone on Jane's team like Van Pelt.Also, why did Jane smile when he found the toothpick in his room. I would think that he may have placed wrong information the Homeland guys found and RJ may also have the "wrong" list of suspects.

Somehow, I think that Rj is not in the list of suspects and based on the fact that he knows a lot of Jane's past carnival life, I strongly think it is Jane's twin brother or something like that.

I am really not sure so please share your thoughts and comments!! 

 
I Found this interesting theory

i think i have figured out who RJ is..It is Reede Smith aka Reede = RED. Smith = tagliaferro

i think it is a very strange coincidence that smith is the english synonym of the italian word tagliaferro. and that his first name is reede. as they love in that show to make word games, i think it is a strong indicatation that he is red john. also, i dont think red john is a dominant or striking character like partrige, haffner, stiles or bertram. rj is the one you would never guess he would be rj. i am convinced it is reede smith!!!and reed here the quotation on sparknotes on the poem "tyger, tyger" (might be a coincidence, or might not :-):"The poem begins with the speaker asking a fearsome tiger what kind of divine being could have created it: “What immortal hand or eye/ Could frame they fearful symmetry?” Each subsequent stanza contains further questions, all of which refine this first one. From what part of the cosmos could the tiger’s fiery eyes have come, and who would have dared to handle that fire? What sort of physical presence, and what kind of dark craftsmanship, would have been required to “twist the sinews” of the tiger’s heart? The speaker wonders how, once that horrible heart “began to beat,” its creator would have had the courage to continue the job. Comparing the creator to a blacksmith, he ponders about the anvil and the furnace that the project would have required and the smith who could have wielded them."

I think any of the seven could be Red John. The only ones that match the physical description are Kirkland and Partridge, rest all are either fat, old or a bit tall. Bruno Heller told we will be disappointed when we find out who Red John is and he could already have been cast. Hence it is axiomatic that RJ could be one who is very self-obvious or someone who has not been shown. Hence it could be the two new characters Mccallister, Reede Smith or Partridge or Stiles and not anyone else.

OMG! Its been so obvious from the start. Red john is Sean Spencer from Psych. He was born in 1976 so in '88 he'd be 12 which would classify him as a kid and he could kill. As a child he learned from his father the power of observation and how to use it just like Patrick. Tiger tiger anyone? In the pilot of psych he has to Be a fake psychic so he doesn't go to jail because he accurately help solve crime from a hotline and they thought he was the killer. But what if in a turn of events Sean was the killer after all and just coming up with ways to frame everybody else so he'd getaway with it. As for the list of 7 the letters in their names could easily spell out Sean Spencer. They do love doing some form of anagrams so what if the list itself is an anagram? Think about it, what other show has had the main antagonist be the main protagonist of another similar show. None that I can think of which would make it historic. Plus it would be a great way to end both shows because let's be honest their both running out of material to make each episode new and not just a rehash of another earlier episode. Mark my words Sean Spencer is red john!!!!!!! The ending of both shows will be LEGEN ...wait for it... DARY!!!!!

I think we are all shooting off on crazy tangents by wrongly assuming that the list drawn by Red John precisely matches the one drawn by Jane.

In the episode, Jane reveals only one name from his list of seven. He is conveniently interrupted before he gets to the other names.The seven names (revealed at the end) are as deduced by Red John (through Lorelei).

Note that Jane is NOT shown to either confirm or deny those names. Indeed, Jane does not utter a single word in the entire final scene. He merely hands over to Lisbon seven photographs (not a list), arranged in the specific order of how Lorelei calls them out in the video. This is easy enough for Jane to do since he has already viewed the video before he plays it for Lisbon.

Jane's own list contains different names - atleast one different name, anyway: that of Red John.

Bruno Heller seems to have confirmed that Red John's name is on the list, but he does not say whose list.

Thus, I feel that Red John will be none of the seven persons whose names are revealed to us. This twist can be easily explained away by merely having Jane say "My list was different" or words to that effect.

Occam's Razor?

For a moment let's ignore the interview where Heller said we can trust the list. I have a question about the CD then. Remember how Lorelei asks Jane to take a look at his list before she reads out RJ's list? Now why would someone as clever as Jane and with as. good a memory make a PHYSICAL list of suspects? Kirkland's men broke in and stole his research. Anyone can do the same, specially someone like RJ. Jane didn't want anyone to know his list, so why would he leave it so vulnerable? And why would RJ think that he will? Now add to the fact that nobody sees what's in the packet that RJ meant for him, the CD is shown in a different scene, there's no hard proof that the CD was in the packet, and that Jane and Lorelei did have enough time to make the video. It seems highly off to me. Even if we can trust the list, can we trust the CD?