Here are very useful source material of animal growls, recorded in Morocco in a very dry acoustic environment (the desert). These sounds would prove to be a very good source for creating your own monster, creature sounds.
These were recorded HD in 192KHz with the incredible Sanken CO-100k microphone. Perfect to pitch down and have fun.
You can learn more about the recordings of these sounds on the blog: soundxplorer.com/camel-growl-vocalizations