I am Red John.

I'm just throwing this out there, obviously, I haven't had time to think all the "what ifs" through.

But what if Red John is some sort of invented persona by the Tiger Tiger Conspiracy?  Kirkland said he suspected it existed so that they could "get away with murder"?  What if they cover their tracks by making it look like a serial killer, aka RJ, did them?  What if they killed Patrick's family so that they could lure him in, having him as an official expert on the case to track a person that technically doesn't exist in order to cover their tracks?  There's a person posing as Roy, Jay, RJ, etc., but the conspiracy uses RJ to cover their tracks for their own sinister purposes.  But they keep Jane and Lisbon alive because they need a team to track RJ, making it look as if they're really interested in catching this sinister individual.

Having said that, I'm personally leaning toward McAllister for RJ, but I'm just mulling over this possibility, too.
 

I just want to point something out here.  A lot of people are focusing on what Red John looked like or walked like or talked like, or how he holds his tea cup or how his hands look.  This from the episodes where we just catch glimpses of him in disguise or from the back or just his hands.  But I assure you, whoever they used to portray Red John in these scenes is NOT the actor who plays the actual character of Red John.  They just use some guy on the set to fill in the space.  It would be WAY too expensive to get the real actor to do these scenes, not to mention the security issue of allowing everyone on the set to know who Red John is.  So seriously, forget about all of these physical characteristics.  Focus on what kind of person Red John has to be.