A city guard walks down an empty street in the quiet hours of the night, and notices a thud come from a dark side alley. He takes a gulp, adjusts his helmet, grips his spear tight, and then moves to investigate. Once at the entrance to the alley the guard pauses, as all the alley holds is a wall of impenetrable darkness. He then squints and holds a hand up to block the light from a lantern spoiling his night vision and waits for his eyes to adjust. After a short while he hears the thud again, which gives him a jump.

"Wh-wh-who goes there?" the guard stammers, his voice weakly cast into the night. Two gleaming eyes reveal themselves low to the ground, staring at him. Why, it must be a lost gnome, a drunken dwarf, or perhaps a halfling sneak-thief? With this realization the guard's confidence noticeably improves.

"I see you there, show yourself!" he commands. That's when the eyes rise up to an imposing height, and the creature's hulking silhouette is revealed.

"You no see Grogg" the figure growls with menace.

The guard's eyes bulge and he nods furiously as he backs out of the alley. He did not see Grogg.

-Class inspired by thread linked in comments.

Modus Operandi

Starting at 3rd level, your Sneak attack can use any weapon you are proficient with.

In addition, you gain proficiency with medium armor, shields, and all simple and martial weapons that are not finesse, heavy, or special.

Death Mark

Starting at 3rd level, you learn to use intimidation as a weapon in combat. As a bonus action, you can make a Strength or Charisma (Intimidation) check against a creature you are aware of within 60 feet that can see or hear you and is not immune to being frightened, contested by the target's Strength (Athletics) or Wisdom (Insight) check (the target chooses the ability to use). If you succeed, you can use your Sneak Attack against that target even if you don't have advantage on the attack roll, but not if you have disadvantage on it, until you successfully use this feature against a different target.

Without a Trace

Starting at 3rd level, you can perform special grapple actions that require two free hands.

Kidnap. As an action, you can use two free hands to attempt a grapple on a suitable creature your size or smaller. Ability checks made to escape this grapple have disadvantage. Until this grapple ends, the target is restrained, cannot cast spells that require somatic components, and it also cannot speak or cast spells that require verbal components if it needs to breathe. In addition, you can free one of your hands at any time by switching to a normal grapple.

Strangle. As an action, you can use two free hands to attempt a grapple on a suitable creature that has a neck thin enough for your hands or a garrote to wrap around. You have disadvantage on the initial grapple check if you cannot Sneak Attack the target. Until this grapple ends, the target is choking and can't speak or cast spells that require verbal components if it needs to breathe. While choking it can survive for a number of rounds equal to its Constitution modifier (minimum of 1 round). At the start of its next turn, it drops to 0 hit points and is dying, and it can't regain hit points or be stabilized until it can breathe again. In addition, the condition ends if you let go of the target with either hand at any time or dash.

Bump in the Night

Starting at 9th level, you have advantage on acrobatics, athletics, deception, and intimidation checks against creatures that you are hidden from, or that have disadvantage on or automatically fail Wisdom (Perception) checks that rely on sight to perceive you unless they can currently perceive you with special senses such as blindsight or tremorsense.

You Can Not Hide

Starting at 13th level, you are aware of the location of any frightened creatures within 120 feet of you, and the target of your Death Mark feature, but only while the two of you are on the same plane of existence.

You can also see in dim light and darkness within the range of your darkvision as if it were bright light, but beyond that you can only see in dim light as if it were bright light, and in darkness as if it were dim light. You can’t discern color in darkness, only shades of gray.

Fear Itself

Starting at 17th level, whenever you roll a 6 on a damage die against a frightened creature or the target of your Death Mark feature, replace it with a 12.