Developer note:

I prefer to keep this page simple and convenient. It's pretty tedious setting it up unfortunately. Please know, this isn't a 1:1 port of the Knocker. It's "my" own actual interpretation of Him, including many exclusive more player like features/behaviors/events for the Knocker entity! It's my own funky little experiment! I have lots of fun coding trying new stuff in the process. I have some history of making interesting horror addon experiences for the community. You are in for something cool definitely! It might feel different, maybe slightly off, but in a very interesting way! You might just wanna experience it in your Minecraft world! You will never feel alone again lol! ; )

Known [DolphinMasterMB enhanced] Knocker behaviors(spoilers):

He randomly spawns at night time,
He usually operates at night time,
He can learn to mess with you at day time too,
He can be spawned with a spawnegg(At your own risk),
Imagine an army of Knockers(Consider your device performance, before attempting this though),
Multiple Knockers can exist independently(Strong device recommended),
He interacts with almost all interactive blocks, doing interesting stuff,
He can craft weapons to expand His arsenal and learns new ways to use them!
He has some interesting(sometimes funny or sarcastic) things to say in chat,
He is terrifyingly playfull and literally a psychopath,
He might have been either a Chef or a Butcher before,
He has an huge but slightly concerning appetite for food,
Never look HIM straight into HIS eyes! To prevent a conflict with an entity you probably can't defeat (Less sensitive on popular demand),
He has unique AI (it's intentionally made inconsistent to simulate a player like behavior),
Even though it's tempting to kick HIS ass, I strongly recommend either avoiding or ignoring him, as you probably won't win the fight,
He is avoidable if you are able to outsmart HIM,
Each encounter with HIM could feel different,
Sometimes it's better to stay inside your cosy home,
He adapts,
He has 5 faces/masks representing: Gentlemen, Murderer, Thief, Pyromaniac and Psychopath (Increased odds for rare behaviors after update),
Those masks each have their own Knocker behaviors,
He has different moods/stages,
He can imitate at random,
He taunts you at random,
His reactions are inconsistent, making encounters unique,
Strategy affects the outcome,
I recommend approaching him with care, as you never really know what he does,
If he seems stuck, don't let him fool you,
He fools people by acting weird,
He acts as a player, but could he actually be a ghost too?,
He isn't always hostile,
He actually knocks,
He sometimes casually whistles, trying to seem innocent and hide His suspicious activity,
He can also be silent on purpose to sneak up on you or does suspicious stuff!
He tries to confuse you sometimes in various ways, Never trust Him!
He baits players,
He lures them into the unknown sometimes,
He can be a burglar too,
He learns when you aren't home,
He can already be in your house messing about,
He visits various homes and structures and could be busy interacting,
He stalks you in various (Endless) ways as soon as He joins your world,
He messes with items,
He loots your corpse,
He can be evasive sometimes after the update to make room for His endless capabilities in behavior being barely used before (Fix),
Even though he has its behavior patterns, you can't expect him to stay consistent,
He might have player like vibes,
All these things will make sense after either playing this addon or watching videos about it, lol! ; )
You really just wanna experience this yourself!
Cheers! ; )

Some tips:

The Knocker supports Vibrant Visuals!

If the Knocker says "Knock knock" in chat, you can respond with "Who's there" or "Who is there" to get a interesting random responds!(EasterEgg only available with Beta Api enabled)

Enable Beta Api for even more cool features and weird interesting Knocker behavior!

Use "/tag @s add silence" to disable the Knocker dialogue and whistling!

Use "/tag @s add friend" to make the Knocker "kinda" friendly! (Not aggressive)

Ps, Can you spot the ominous sneaky dude in the screenshot above?

DolphinMasterMB's interpretation of The Knocker