A note about the writing in blood from episode 1x11 ("Red John's Friends"):

"He is mar" or "He is man". A man dying as he was would be pithy with his comment. If it were a name, he would have written the name, instead. No, he was writing something else:

"He is many."

At this point in the series we only knew of Red John as a serial killer. We did not know it was an entire cult. This message was a hint that this was planned from the beginning.

How else could Red John command the power and influence necessary to carry out his activities? The hint is reinforced by the episode title.

My theory is that Red John is a secret cult within Visualize. It may be that it is considered the highest echelon of Visualize, but more likely it is a splinter group within the organization that recruits from within. There is likely a charismaric leader, and that person is likely not Brett Stiles, and if not then Stiles would know who it is and fear him.

I'm afraid things are much darker than were originally anticipated. The biggest clue towards red john's identity was the poem the tyger by willliam blake and only person has extremely deep understanding of that poem and it's metaphors. That person is William Blake.

Tyger! Tyger! burning bright
In the forests of the night,
What immortal hand or eye
Could frame thy fearful symmetry?

In what distant deeps or skies
Burnt the fire of thine eyes?
On what wings dare he aspire?
What the hand dare sieze the fire?

And what shoulder, & what art.
Could twist the sinews of thy heart?
And when thy heart began to beat,
What dread hand? & what dread feet?

What the hammer? what the chain?
In what furnace was thy brain?
What the anvil? what dread grasp
Dare its deadly terrors clasp?

When the stars threw down their spears,
And watered heaven with their tears,
Did he smile his work to see?
Did he who made the Lamb make thee?

Tyger! Tyger! burning bright
In the forests of the night,
What immortal hand or eye
Dare frame thy fearful symmetry?

Heller leaves it all open, they give themselves plenty of room to move
within the script. If they see something works they go with it. If it
doesn't they change. This then changes everything.

They are not
going to keep going with something if it doesn't work and right now this
Red John thing is keeping people guessing and it's working, so they
will keep screwing with us until their pockets are full of money and
then when they feel they have milked this Red John thing long enough
they will just create 2 episodes, get bits and pieces off all the worst
bits of who they wish, create an episode around that and bingo, there's
your Red John. Teresa could be Red John as far as we know, anyone could
be Red John. Just Teresa with her hand in a bandage could change
everything.  Get over it people. This is the reason no one can work out
this mystery. It's a scam!

I'm really new to this series, just started watching a couple of months ago, but one thing that caught my eye immediately is that the "smiley" face looks a lot like Patrick Jane. I'm sure that may sound odd, but there are times when he smiles that I think he looks like the smiley face. It's drawn with the eyes slanting down and his eyes do as we'll. that leads me to think it is someone from his past that may or may not have been revealed yet. Also red John supposedly paints the victims toe nails with their own blood. What Man would do that or even think to do that unless he's on the feminine side or its a woman, insane or scorned maybe. What is the story of Jane's mother? How about his psychiatrist? Wasn't that a female? It just seems that everyone is looking for it to be a man, but the men that are listed seem a little obvious. Sorry if this is really naive....:-)

I think we interpreted the 5th season ending wrongly. The writers want us to think that red john is still a step ahead of red john and what not but what I think is that Patrick Jane wants Red John to feel that way. By making that list and letting red john "predict" it correctly, he has made red john more cocky and desperate to prove that he is the best. As red john put it himself that he will start killling again..and that is the window jane needs to watch his suspects even closer and wait for a mistake to happen. Of all the things we know about patrick jane, one is sure: he is smart as hell and this time it is red john who has fallen for his trap. 
Patrick jane victimized himself to lure rj out. 

HELLO to all the fans out there...

Here's my theory...,
        
                                   Red John is not a powerful person as an individual.I am guessing he is just a random guy who has access to all the dirty secrets of his accomplices. all of his accomplices were forced to bond with him because of their dirty secrets. he is not a sociopath , most of the RJ victims were killed because some one wanted him to. gradually he becomes popular , more secrets which means more money and power.
 
i mean HOW CAN ONE SINGLE PERSON HAVE SO MANY PEOPLE IN HIS HAND..?

i guess Red john is an ex-cop or present low profile cop who has access to all departments. or maybe he was from visualize who helped stiles by killing two men. then he kills so many people for a lot of other people in return he gets money and finally killing becomes his hobby. he kills for fun.

i also have another guess that RJ has some connection with patrick's wife and her family.

so basically red john is not someone in the CBI ,  but someone whom we are not taking account of...
i am guessing he may be a cleaner tooo...

Hello guys, well I'm a huge fan " The mentalist" the thing is, my theory its simple, just look and if you really like this episodes so you should know that the possible of Patrick Jane can be RJ its totally false. I tell you what, Patrick Jane its too smart to be RJ. Patrick Jane never could killed his family, doens't make any sense right? Now, in the CBI. RJ has around 3 friends ~ and 2 high friends. As you can see RJ has many powerful friends, like FBI, CBI, etc etc. Kirk is his cumplice no doubts. But is too obvious right?  Now, Patrick Jane "Killed" RJ. Yes he killed one of his "important buddys" for seconds i tought really that Patrick Jane killed RJ, because when the man died, RJ didn't killed any victims, so why? I mean, he is a serial killer right? :P The thing is. RJ doens't exist yet I mean, exist but it's changed everytime you know? Because Patrick Jane is too smart and he can catch the real RJ so easy, the problem is when he is close to catch him, something always happen am I wrong? For example, RJ never show his face or something, he just kill. So, I think Patrick Jane gonna catch him in way so awesome that we all gonna be like "O-M-G" It was a perfect episodes, you will see.

The only thing that I can say is: No one knows who RJ is. And all the suspects you mighty think they are RJ, are false.

Keep at good work' Simon Baker.