Terrifying vocals!

I don't see how they're terrifying, though.

Silencer and early Bethlehem takes the cake as far as I'm concerned.
 
No brutal DM vocals are in anyway scary, let alone terrifying, half of them just sound ridiculous.
 
Tom Araya, Tom Angelripper (Sodom), and what's-his-name from Kreator all sound pretty badass and scary at times.
 
Dani Filth


....


(lol)

but seriously, Nergal (Behemoth)
 
To be honest I think the only vocals that have ever 'scared' me at all are probably those in The Angelic Process. Likely something to do with lack of sleep + darkness + multiple intoxicants but aye.
 
Sortsind's Sår (Particularly the track 'Blandt Grå Monumenter')
Dark Tribe's In jeraspunta - Die Rückkehr der tollwütigen Bestie
Bethlehem's Dictius Te Necare
Sort Vokter's Folkloric Necro Metal (Mostly one particular vocal line in 'Hatefulle Tanker', it's unmissable)
 
I second stuff that Malign, unknown, and others have posted, and I'll just add obvious recs like:

Demilich- Nespithe
Urfaust's Geist ist Teufel
Beherit- Drawing Down The Moon
Paysage d'Hiver- Paysage d'Hiver
Mgla- Presence
Traumatic Voyage- Traumatic Voyage/Traumatized

You get the picture. I do have a strange sense of what I find "terrifying" in vocal styles, but the vocals on these albums all give me a sense of discomfort that I associate with this sort of request.
 
If it's in the Black Metal vein, I would highly suggest Hekel "De Dodenvaart". The guy has vocals which sound like he's swallowing glass shards, it's brilliant. Awesome album also, but under-rated imo.
 
Galder.
Blakkheim.

Atleast kids or people not use to extreme metal(maybe some into metal) would find both Terrifying!. That's all I can think of to me that resemble terrifying vocalists and both are atleast really intense and extreme.