This question already has an answer here:
Amongst sailors there is a superstition that assigned the expression "Jonah" to anyone who is considered to bring misfortune or bad luck (Ref. https://en.wikipedia.org/wiki/Jonah#Jonah_in_sailors.27_superstition).
I would like to know if there is any equivalent slang for a person who intentionally spreads gossip or false rumours, or, let's say, someone who is considered the rotten apple (or black sheep) in a group and normally the one responsible for destabilizing or segregating this group. (I have such person in my family!)
I've already read the article What is the single word that describes a person who always gossips? but those expressions don't quite fit my question since i'm looking for a slang or popular expression.