How do people stop others from harassing them?

[I want MOAR]

It happened to Scooby on youtube and he move house and take down his entire youtube channel, which he had since 2006.
Recently I heard on the news about this case of extreme harassment. This person took photo's of this guy off of his facebook and photoshopped them like people photoshop fakes of celebrities. Like he took his face and put it on the bunch of gay pornographic actors. He messaged the link to all his friends on facebook and mailed the photo's to his parents and workplace. He had to move home and take all his information off the internet. This person was harassed for 2 years before he was able to get it to stop.
They got the police involved and this person harassing this him lived in Bogota in Columbia. Law enforcement there were contacted about him but nothing was done.
I can't believe how bad harassment can get. I've pretty much shut down everything except for my email on the internet.
I've got facebook but photo is discrete and my friend list is kept private. I only add people I know.