This pack makes monsters far more scary and intense.
I sampled many different video games to get the right sounds for each mob, such as:
doom, Skyrim, Call of duty, Dying light, SCP secret lab, and others.
I take no credit for the sounds this is just a mash-up.
This mod works really well with the sound filters or sound physics (both client-side) mod. I would recommend using Drago's creepy mob's resource pack, as it makes the mob's eyes glow. That along with the Chocapic's shader with lots of fog will get you a great scary gameplay.
Zombie Sounds:
Enderman Sounds:
So many other monsters that are scary as well! Download the mods and listen to the others!
Good luck Minecrafting!