Please read before judging. Not a Solid Theory but a lot of ideas in mind.

Huge Fan , Haven't skipped an episode .  I have a crap load of theories and I am really confused about Who Red John Can be So i'm looking for your guys opinion so comment all you want. i need someone who is a critical thinker perhaps somebody with a more better answer or someone who has looked alot more deeper into this than me. Lets look at the facts. Okay of course there are the 7 names revealed in the Season finale 

♦Bret Stiles   
♦Gale Bertram   
✗Bob Kirkland   
✗Ray Haffner  
✗Reede Smith   
✗Thomas McAllister   
✓Brett Partridge  ( We all know why the people with a [✗] by their names have gotten an ✗  . No need to explain because we Know that they don't fit the description/criteria. People with the [♦] are suspects that i can't completely rule out. And of course the main suspect)
 
However i Feel as if There has been Way too many connection through the CBI along from season 1 to just have a single killer . . I'm a believer of the red hearing theory , and also . There is the signature description of Red John Through Rosalind Harker, who happens to be Blind which is a key detail.  

Red John is most likely  Caucasian
Rosalind described him as "just under 6 feet tall"
Red John has short straight hair
Red John either has or puts on an odd, high pitched and soft voice
Red John should be older than 30 years (since his murders date back to the 90's)

Bret Partridge fits the description all to well in my Opinion but an instinct in me tells me not to go along with it. I wan't to know if it's possible that Red John could be tricking Rosalind since she is blind . Other accomplices get killed or commit suicide after Red john is finished with them . is it possible that he hasn't done it to Rosalind since she is blind and there are details she can't see on him , although she knows a lot about him?. 

 If Bret P. is Red John then how is it possible he is always one step ahead. Someone like Bertram would only be able to know what Jane is doing , And if So then he has to be in connection with Brett P.. in some way. 

Lastly the red haring . My mind is telling me Brett P. Because of his Voice and physical features yet we know Red John wears a ring on his left hand shown in season 4 . 
Here [ http://i.imgur.com/UZGYhAl.jpg ]

Brett p. is Not wearing a ring here  [ http://i.imgur.com/erDT36y.png ]

Kirkland Nope [ http://i.imgur.com/Emn4cbH.png ]

Stiles No [ http://i.imgur.com/e7uvgso.png ]

Haffner Negative [ http://i.imgur.com/YLC8HCc.jpg ]

Sheriff McAllister Nada [  http://i.imgur.com/b8KhrTg.jpg ]

Smith not even * Hes very overweight so hes excluded *

SO Whos left ? Ding Ding Ding . you guessed correct 

Bertram [ http://i.imgur.com/ifJRtcr.png ] 

BUT! He doesn't fit the Red john description He's Fat , Bald and his voice is not so sweet. Now This means either He is an accomplice or they both take turns doing whatever it is that needs to get done .

The list from the Season 5 Finale is legit.

http://insidetv.ew.com/2013/05/06/mentalist-finale-season-6-red-john-list/

This is my first post and I really don't have a guess who Red John is.  I would, however. like to discuss some things from the series as I have seen it.

I think that the secret on how the memory was detected by Red John has to do with Patrick's stay in the mental hospital.  He has no set memories of what happened during this time ,and I believe that a psychiatrist helped him.   He  seems to have only fond memories of her.   She, however, may have discovered the memory during his treatment and told Red John what the memory was about. 

I really think that Lisbon is the key to this epsiode.  She has an injured arm (from where we don't know)) and was the only witness to the end scene.  I think that she was essential as Patrick already knows from the DVD what the list was going to be.  He gets her to deal out the suspects (not him) ans she seems genuinely surprised.  I think the final scene was an act for her and will serve Jane's discovery of Read John.

It took me a while to write this whole theory so please read before upvoting/downvoting.

We know, from an episode in season 4, when Roy pays Rosalind a visit and kills the morgue attendant to prove he's alive, that he wears a ring in his left hand: http://i.imgur.com/UZGYhAl.jpg (that pic is a little blurry, but if you see the episode in HD, you'll definitely see it).

Brett Partridge, the most likely suspect, doesn't. Here's him in episode S05E15, Red Lacquer and Nail Polish: http://i.imgur.com/erDT36y.png 

As for Kirkland, he doesn't wear a ring either, and he holds his drink with his right hand: http://i.imgur.com/Emn4cbH.png

Haffner - no ring: http://i.imgur.com/YLC8HCc.jpg

Same for Stiles: http://i.imgur.com/e7uvgso.png

And finally, Sheriff McAllister, no ring either: http://i.imgur.com/b8KhrTg.jpg

As for Smith, I couldn't find a video where he shows his left hand, but come on, the guy doesn't fit the RJ profile at all. Red John has a rather slim figure (not soft but not beefcake, as described by Rosalind Harker) and, according to the writers, his real face has been visible in episodes before season 4 premiered. This guy first appeared on S05E01 and I'm not sure if he even had any lines. I think it's safe to rule him out.

Bertram, on the other hand (well, not literally) DOES wear a ring: http://i.imgur.com/ifJRtcr.png

If the list can be trusted (and Heller isn't screwing with us), then, judging Roy Tagliaferro's appearance, Bertram is Red John. There's also him calling Patrick "boy wonder" in S03E01, his William Blake quote, the mall scene in Strawberries in Cream (how else did the fake Red John know he had to be at that particular mall at that exact time?), his resemblance to the mysterious police car driver in S04E24, etc.

There's however, other things that don't match. He's over 6 feet tall and he's mostly bald (according to Harker, Roy has short hair). The rest fits, though.

I am the only one who thinks Robert Kirkland is a 'good' character?  I think he is also pursuing red john like Patrick Jane.

I just wanted to get this off my chest. If that sherrif guy ends up being Red John I'm going to flip a table. (╯°□°)╯︵ ┻━┻