I hope it's OK if I make a thread of something that has been requested, I just felt the other one was too barebones and that could hurt its chances.
This plugin is not hosted on Spigot but it is completely open source and has been maintained since 1.8 with no wrongdoing found since then, originally it was an updated version of the abandoned Herobrine AI project which is included on Aternos but with Version 2 it's been fully reworked and is thus completely original on a technical level. It's very fun to play around with, adds to gameplay and is an effective way to surprise or scare your friends.
You can find its page on SpigotMC here, it's simply called Herobrine or Herobrine 2 (by the repository) ever since it was reworked and it has been updated all the way up to 1.16.1 with a 1.16.2 version likely coming soon. Here's the official website.
Thank you all for your hard work and dedication and I'm really sorry if I shouldn't have made a thread whether it's more detailed or not