Red John is not a woman.
Assuming time and space exist, Red John is not Patrick Jane.
Red John is under 6 feet. (aka: NOT Walter Mashburn or Wayne Rigsby) 
Red John is not fat, chubby, flabby, or soft (aka: not La Roche)
Red John is alive. 
Red John is not in prison. (aka: not Dr. Roy Carmen) 

This eliminates more than half of the people on this suspect list. 
Why do people keep posting theories that contradict known Red John facts.  

I just watched episode 7 but after having already watched episode 8 and the very last scene of episode 7 is a handshake between Agent Kirkland, Homeland Security, and in episode 8 Lorilei talks about a handshake with Red John. Could it be him??

It is NOT Rob Kirkland!

Red John knew Jane way before Rob Kirkland found out who PJ was.

It is Moriarty!!!

I found this picture online of the guy.

http://shaddicted.tumblr.com/post/31807377749/bylarge-shaddicted-sherlock-the-mentalist

His name is Agent Moriarty. It's like a Sherlock Holmes crossover. Remember in one of the season finales the guy who said "Red John is a friend of a friend of mine." The one Jane had to break out of jail that got away in the end and fled to Mexico only to wind up dead with a hooker in the bathtub. He wrote on the wall "He is MOR–" MOR are the first three letters for Moriarty.

Alright for one, I think of Roy Tagl. as a sep. thing from Red John. Roy is more or less like one of the main guys in the group and all but there are many people in it such as virgil minelli, kristina frye, lorelei martins, the many people we saw were underlings including the guy at the farmhouse drinking the tea. Why do I say this? simple, unless someone has been pulling off some impressive acting i have yet to see a better mentalist than jane is, i know some people say his dad but come on he'd be like 70 or so which makes it a bit hard to believe.

The story of how Roy meets Roaslind seems odd in itself. red john just happens to break down or something and happens upon her house? people say she seems hynotized when jane and them show up and she is playing the piano but she answers their question about roy leaving. why was the morgue attendant actually killed? i highly doubt red john cares much if people think he is dead or not so he wouldn't worry about it unless something that man said or did insulted him. if red johns car breaks down with his resources and all hell i would think he would have a driver and more at this point, which comes to also another odd point.

why was luther wainright in the car at all i mean they could of just grabbed about anyone and tossed them into that situation and was he really dead even? it seems odd that darcy had a mental breakdown i also find it odd how they leave passages unchecked. the twin sister who lived why was she not spoken to? could she have seen red john or roy or someone else we'll never know...what did that little girl tell jane in the time before the cops got there, when they do get there he is teaching her the quarter trick which more often than not is how he hypno's people which means he had all the time in the world before he called the cops to get the info. it is unlike jane to just not hypno her to find out hidden info she may have issues thinking of normally.

also we keep seeing odd cars like the 70's car at the funeral and the police cruiser chasing after the fbi. also with all red johns kills in other states itd be kinda odd for him to be a cbi member now fbi or homeland maybe but bob kirkland is way too simple of a person to think of. we cannot associate rj's voice with him himself as that is prolly another way they have been leading things on with people also the fact roy got sloppy with rosalind just seems odd the po box and all that naw roy or red john knew jane would find this info or else they would never have hired a sky writer which caused the info to come out. rosalind says she hasnt seen him in a long time but we see him using one of her tea cups so if she is lying about that what else can we believe of what she says even if what she is saying she even knows is true or not.

Ok, Lorili said Jane should have become life long friends w/Red JOHN when they first shook hands. Jane shook hands with the guy who was part of Homeland security on the episode where the news reporter was killed by the T.V. anchor and the wealthy guy who got away with it. He told Lisben TO BACK OFF. THEN ASKED HER TO GO OUT FOR COFFEE.

I belive Red John might be Patrick Jane's father.

There was a murderer who Jane provoked to offend Red John and RJ killed him afterwards. The reason was the exact reason that provoked Red John to kill Jane's family. Only this time, RJ killed the offender, not his family. So why would Patrick Jane be spared? Because a father cannot kill his son.

Also, one might agree that for a serial psychopathic murderer there would be some fun in playing games with a smart cop, but Patrick Jane is, indeed, a pain in the ass for anyone trying to commit crimes. So why keep sparing him? Why, instead of getting rid of him, RJ keeps trying to get him on his side?

Thirdly, Patrick has mentioned that Red John is someone better than him at cold reading and stuff alike. We've all seen, in Jane's flashbacks, that his father taught him how to do everything he knows. So one better than PJ is only his father, having the advantage of knowing his son's patterns and everything.