Anthropmorphic Personification and Sentient Cosmic Force: of fear, manipulation and cruelty.
Bad Boss:
Creepy Child: Or at least, the appearance of one, its' preferred and often used form is that of a creepy young girl that's extremely pale in color with glowing red eyes and sharp teeth, combined with its' use of a much older, raspier man's voice instead of a girl's voice and you get a very unnerving and creepy effect.
Cosmic Entity: A given being a Entity.
Deal With the Devil: Did this with the Drukhari, freeing them from Slaaneshi's reach but also tying them to it in turn, forcing them to become even more monstrous then they were before, which is rather impressive given how awful the Drukhari were anyway.
Dimensional Lord: Like all of its' kin, it has its' own realm within the Plains of Rebirth, aptly called the Realm of Greater Horrors, which name pretty much confirms what goes on in it.
Furthermore, the Haunting Voice is known to create smaller, independent realms purely so it can drag off a variate of a person or multiple persons into said smaller realm entirely so it can torture and torment the poor being in various horrific ways, one notable example being it taking non-Known Multiverse variates of various CN, Nicktoons, DC, Anime/Manga, Disney, and other animation settings to smaller realm meant to be a twisted and monstrous parodies of their worlds torturing and killing (and reviving) them constantly over a unknown period of time.
Eldritch Abomination: Like the rest of its' kin, its' this by default, although its' not as noticeable given its' preferred forms but it has and will gladly turn into much more horrific example of this in all manner of ways.
A Form You Are Comfortable With: Or rather a form you are uncomfortable with, no matter what form it takes, the Haunting Voice always picks a form that is going to unnerve and scare beings no matter what.
God Is Evil: Given it frequently goes around tormenting and torturing people just for the hell of it, the Haunting Voice falls into this by default.
I Have Many Names: Since the Entities don't have true names and thusly called by all manner of names over the eons by unknowable number of sentient species, it too has this as well, and most of it relates to its' behavior and general actions, like The Tormentor, The Bringer of Nightmares, and It That Birth Horrors just to name a few.
Jerkass Gods: One of its' many names is The Tormentor, it obviously falls into this.
Lack of Empathy:
Manipulative Bastard: Frankly it not being this when it embodies the very concept of manipulation in the first place would be the surprising part, and unsurprisingly, the Haunting Voice is the greatest manipulator among the Entities, though never able to manipulate the Planter or the Hunter.
Mindrape: Its' preferred method of tormenting people, going into their heads and psychological torturing them via their own fears and traumas, that said it is capable of physically alternating the environment for various reasons, it simply finds more fun in torturing people psychological then physically.
Reality Warper: Granted all Entities can do this but the Haunting Voice is among the Entities that is known to use this the most, often times by warping a area into some twisted nightmare realm to slowly drive people mad and or brutally kill them.
Sadist: While certainly not anywhere near as sadistic as the Hunter but it is regarded as the second most sadistic of the Entities, and unlike the Hunter, where its' sadism is something unique to it, the Haunting Voice's sadism is partly influence by one of the aspects it embodies, cruelty.
Time Abyss: Par for the course for a Entity, since all Entities are outright stated to be so old there can't be a word nor a number to come close to describing their age so the same applies to the Haunting Voice.
Vocal Dissonance: A frequent way it screws with people is to use voices that don't belong to something or more horrifyingly, take someone they knew or worse a loved one and twisted it into something monstrous.