No, there’s no evidence that ghosts exist! (Thankfully).
For this reason I don’t believe they exist and the fundamental concept of ghosts, a persons personality continuing in an earthly but not physical form certainly contradicts biology and cognitive neuroscience.
There have actually been a series of creeped out scientific researchers that have felt that something or someone is there when working late in the laboratory to find that the source of their anxiety is inaudible low frequency sound waves from some equipment!
Making them feel funny. As in Scooby Doo, there is always a better explanation!
I am not aware of any scientific proof for ghosts. I don’t believe in the whole malicious/evil ghost thing- why would some people turn into ghost and not others and why would they want to harm people? Also, if everyone turn into ghost, do all animals turn into ghosts too? How about plants and bacteria? Wouldn’t they run out of space? Maybe the whole thing is just beyond my understanding.