The "Unique" monsters (purple titles) are always found in the same place. There's actually quite a few already in the Beta: Headclever, Sarkoth, and not coincidentally The Skeleton King since he's a boss. Feel free to add information about where they might be located, and what their abilities are.
The "Rare" ones (yellow title) can randomly spawn in designated areas. Some areas they actually can't spawn (like Old Tristram Road normal mode). These will have generated titles drawn from a pool of names. So far we know all the possible names that can be generated, and that there are in fact pools of names for specific abilities (like Molten can get "Vulcan", "Pyros", or "Foulstew") and generic ones, but we don't know how it decides when to use which pool. The least that can be done here is just a list of the names and their association - again feel free to start even with a simple list
You can figure out the names from other places on the internet, like here for example. This is also a good place to figure out the levels of the monsters.