Bugbear Boogeyman build?

[Rfkannen]

The new changes to the bugbear (they are the same but can fit in spaces sized for small creatures and have fey ancestery) have got me thinking it would be fun to make a bugbear boogeyman, really lean into the mythology behind the bugbear. Be stealthy, hide under peoples beds, frighten and terrify your enemies, and generally play your classic monster in the closet/under the bed boogeyman.

How would you build a character like that?

[Heavenblade]

Reach can also help with that (hiding under the bed and pull in the creature sleeping above, etc.)
I thought about similar concepts in the past, and I think that a warlock works really well here. One with the shadows is SUPER favorable for this kind of character, and relentless hex is just so fun in this context - you are alwats just barely in the eyesight of your chosen target, but somehow they can't seem to escape you - and if they do anything but run away, you catch up to them and still have the time to hwack them once or twice.

Some other cool invocations -
Bewitching whispers is also really appropriate here, even though its not that strong of an invocation, mask of many faces/misty visions in order to drive your hunted targets crazy.
I'd suggest pact of the tome for some fun divination spells, ways to hunt your target and stalk it over a long time, etc.

[Dualight]

Speaking of sneaking through the shadows, Gloomstalker ranger is great for being "the thing that goes bump in the night" as even creatures with darkvision won't be able to find you by sight in the dark. At high levels, Shadow sorcerer works well for being able to teleport freely in low light environments. Way of Shadow monk would give a (much)shorter ranged but otherwise better version of that far earlier.

[OBoyd]

Fey Wanderer Ranger/Undead Warlock is creepy and crazy good.

[Stangler]

Gloomstalker + Beast Barbarian (climb on walls) plus attack with claws which seems appropriate.

You can even get the tavern brawler feat to grapple from the ceiling you are climbing on.

[Psyren]

You'll want a build that gts multiple attacks. The Surprise Attack ability was buffed to (a) no longer require the surprised condition, just that the target hasn't acted yet, and (b) it's no longer once per combat, so if you can get off multiple attacks on creatures that haven't taken their turn yet you will get the 2d6 damage boost on all of them. In addition, as it's a die roll boost to the original attack it should get multiplied on a crit. Bugbear Assassin could be an interesting build.