Free: Marie Ork
Marie Ork is a voice bank for the free Plogue Alter/Ego synthesizer. She was created from recordings of a female death metal vocalist, but is capable of much more than just death metal growls. The original version was an entry in the 2016 KVR Developer Challenge. Alter/Ego can be downloaded from Plogue's website.
If you are wondering how to use Alter/Ego, we've collected some tutorial videos on another page.
She can be used as a virtual vocalist who can both sing and growl, a source of monster voices and sound effects for game and film audio, and a synthesizer which generates strange textures. Her voice bank contains four voices: clean singing voice, talker, growl (noisy unpitched vocal) and space (capable of producing a discernible pitch, just plain weird). All the growl and space voice recordings were of English phonetics, while the clean and talker voices add a few extra phonemes for Latin. Japanese is also supported, but will have an accent. More than 50 presets are included ranging from conventional singing to dubstep basses. The total download size is 652 MB. This walkthrough explains her general functionality. Here's a short in-character song featuring both growls and clean vocals, and very orcish lyrics! There are many more tracks on various sites out there, of course.