What are the potential rift bosses?

Last night, while doing some Nephalem rifts, I encountered both "The Butcher" and "Zoltun Kuule" as rift bosses, only they were renamed slightly (The butcher had a different name, and a subtitle of "Meat Chopper"). Both retained several of their boss abilities from their original Acts, but this was the first time I'd encountered former bosses in a rift. Others seemed to be randomly generated champions. Does anyone know, or have enough experience to say, where the rift bosses are picked from?

Here is a non complete list of rift bosses :

• Agnidox (N/A)
• Bone Warlock (N/A)
• The Binder (N/A)
• Blighter (Herald of Pestilence)
• Bloodmaw (N/A)
• The Choker (N/A)
• Cold Snap (Izual)
• Crusader King (Skeleton King)
• Ember (Nekarat the Keywarden)
• Erethon (Death Maiden)
• Eskandiel (Malthael)
• Flesh Carver (The Butcher)
• Gluttony (Ghom)
• Infernal Maiden (N/A)
• Lord of Bells (Cow King [Easter Egg])
• Mistress of Pain (Cydaea)
• Perdition (Rakanoth)
• Perendi (Mallet Lord)
• Raiziel (N/A)
• Reformed Warden (Warden)
• Rime (Xahrith the Keywarden)
• Rokrak (Fallen Champion)
• Stone Singer (Sand Golem)
• Sand Shaper (Zoltun Kulle)
• Satrix (Writhing Deceiver)
• Spider Queen (Queen Araneae)
• Tethrys (Succubus)
• Voracity (N/A)

I'll complete and cross check it later with data from achievements.