I would also add Gabriel Gonzaga to the list. Probably a lot of guys out there like Mike Russow who were clean, but they never got that elite level. Gonzaga did fight for the title and KO'd Mirko when he was top 2-3.
I'm nearly positive Gonzaga has been clean, because I live in the same town he has. I was part of an MMA promotion here for a 4 year period from 2007 to 2010, and when you are involved with it, you know who is using what, which teams have the most users, etc. I never once, from anybody (even the most jealous gossipy idiots in the entire scene) heard Gabe's name brought up in that kind of conversation.
If you don't take my word for it, take a look at the guy's physique and how he's naturally aged and slowed down at the same time greatly. If he was using it's almost a guarantee I would know. I can't go into detail really because my name is attached to my account, but I was not just acquaintances, but even family, with people who sold gear to fighters in the area. I have no doubt if THE most high profile UFC fighter that lives around here was on gear, I would have heard at least something.
This was all pre regulation too in my state. Zero testing, wild west times. Not that long ago really..