I chose "someone else" because the dropdown's choices were all single individuals. I'm skeptical that it's as simple as Red John being one of Jane's final 7 suspects. Yet Bruno Heller said, "You can trust the list." What's the trick or catch? Well, how about if Red John is two people ... one who does the killings, the other who's the mastermind? Anyone on the list is capable of being the killer, so in that sense, we can trust the list. But is the mastermind also on the list? Maybe, maybe not. Personality-wise, who's the only person with the charisma and intelligence to match wits with Jane. Only Brett Stiles. But remember Jane said Stiles couldn't hurt a fly. Not personally. So he had someone do his bidding? Or maybe it's someone like Walter Mashburn, who's not on the list and arrogant enough. So who's methodical enough and cold hearted enough to be the killer? It would have to be a someone good at keeping secrets, as well as someone smart. And someone on the list. I like Kirkland for that. The others have some screw loose that would make them risks for Red John to trust. We already know Kirkland killed for Red John. Anyway, that's one way to "trust the list" and still have a twist, even someone not on the list.

       I'm sure by now everyone has heard the theory about the "Red Shirt Guy" who is sitting in the food court during the final episode of season 3.  If you're not familiar with this theory click this first link. It's a short video.

http://youtu.be/590v4FCm6WU
http://www.youtube.com/watch?v=590v4FCm6WU&feature=player_detailpage

    Now, what many of you may not know, is that this same man can be spotted in season 4 episode 9.
Around 35 secs into this video he is sitting on the roof top wearing a suit, while Jane and Lisbon enjoy their icecream.  This is obviously the same man. Short, dark hair. Medium build. Wearing a business suit......Oh did I mention the name of the episode is "THE RED SHIRT".  
           I would like to hear you all expand on this theory and share thoughts. And is that the CBI rooftop we see so much?  Anyway watch the clips and take a look.  Open two windows and take a look at the guy....

http://www.youtube.com/watch?v=hAs5hLQftwI&feature=share&list=PL3A4A9B97CBA34A29
          

Hi everybody! First of all I must say that there are a lot of interesting theories here and almost every possible theory is already introduced. I have to ask all the fans to avoid posting already existing theories, because it's very hard to navigate through the whole amount of almost 4500 posts.
But the theory I'm going to introduce is newly generated likely, so here it is. Red John is... Raymond Harker.
Imagine a story of Harkers, who had two children (even maybe twins), a boy and a girl, Raymond and Rosalind (these names are similar enough to be given by the same parents). Once the girl got sick and Harkers asked some healers for help. Unfortunately, the healers (the Janes, father and son) were fake and this led the girl to blindness. The girl was very smart, but mentally disordered and seeking revenge to the whole world. Being unable to act herself, she began to use her brother Raymond.
But once Raymond made a mistake not killing Miranda Roman (Martins), who managed to write something on the floor before death. Miranda wanted to write Raymond, but was powerless, and her message was interpreted as Roy. And genius Rosalind became to an idea of creating some new person, Roy. So she gave a name - Roy Tagliaferro. So that name became some kind of cover for her brother. Later Jared Renfrew, who probably knew about the massage left by Miranda, started writing "He is" (there are two of them, that's why writing "He is" before the name, because there is a female as well), then realized that he's dying and wrote only the next part (He is MON), hoping that somebody could merge the two messages (RAY+MON).
At some point they realized that it would be safer to hide the fact that they are brother and sister (likely twins), so one of them should change the surname. So Raymond Harker became Raymond Haffner (look at the letters, not very hard to fake rk as ffn). By the way, look at their faces, aren't they similar enough to be twins?
So, physically RJ is Raymond, but the mastermind is Rosalind.
P.S.: Maybe at some point Dean Harken was considered to be the brother. Also Grace Van Pelt seems looking like these two, so maybe she is the third child.

Patrick Jane's father could be Red John. Patrick left his father tired of cons. No-one knows his(father's) life after that. But Patrick appeared on TV with physic cone and commented about Red John. Again, Red John plays with Patrick and wanted to be a friend and associate. His father always believed together they made a good team).Not that he wanted to hurt him. In 5th season Red John kills someone(girl) who was a good memory for Patrick from his childhood and brought him back to his hometown.
Who else other than his father could know a secret childhood memory.
Also the girl who died lived with his uncle who was a partner of Patrick's father.

I also strongly believe there is a helping hand inside CBI for RJ.
Could not be one of the seven suspects because RJ would not have spared them since he knows PJ is suspecting them.

None of the characters that were listed as prime suspects by Jane can be Red John.
When his private office was spied and information collected and given to Bob Kirkland, thanks to the stick Jane inserted between door he knows he's been spied but he dosen't react as this is a plan by him. He now wants RJ to act and Jane will be the one who will play him unlike earlier. 
But who Red John is?? The final season where his identity is gonna revealed starting September on CBS its a must watch to find out..

I've read many of the theories posted here and found many of them very credible, but I'd like to add another that was hinted at by the author of Theory #4388 (?).  There is more than one RJ.  I'm not sure if it is all seven suspects, but it is two or more men. Why?
   
These are men who with sado-masochistic tendencies. The gruesome nature of the murders and the fact that they are serial killings suggests this.  The RJs found each other through their B&D fetishes, but have taken these a step further. They must now continue to kill, not only to pursue their fetish but also to cover up the earlier crimes and those who could expose them.

Consider the array of "disciples" or followers that RJ has.  It's hard to believe that one man could assemble such a group and not be exposed unless several other members are RJ and the disciples think they are, like them, just disciples.  Or, they may be the loyal servants in a B&D relationship with one or more of the RJs and thus can be used by the others.
Second, RJ has an uncanny ability to deal with threats quickly and efficiently. Jane isn't chasing one man; he chasing several.  Each can probably provide an alibi for one or more of the murders, but not all.  That's the wild card that keeps throwing Jane off the trail of one suspect and why he has seven.  Jane actually killed one of the RJs when he shot and killed that so-called disciple (I can't recall his name) in the mall.  Yes, the man said he was RJ, but so are others.
Any thoughts??    

All of you just say "Bob Kirkland and Jane didn't have enough time to become friends" so please explain me in the comment, why had Jane even put him on the list?

I also thinnk that Bruno Heller didn't think about all that details you are obsessed with while he was working on the 3rd season. That was 3 years ago folks, Red John wasn't the main obsession then.