I've had two stalkers, that I am aware of.
The first was when I was 15-16. There was this guy, who I found out later didn't even attend our high school, who was friends with my friends and I considered a friend. He would always be around after school at friends' houses and want to walk me home from school, etc. It started getting creepy and a friend told me that they had expressed to other people about their interest in me. I tried to distance myself, but it got to the point where they would follow me everywhere. One night at a friend's party they followed me into the bathroom and raped me.
I became a recluse and distanced myself from all of those people. I have PTSD and severe social anxiety still, over 10 years later. When it happened I was terrified about telling anyone about it. Eventually, years later, I went to the police, but I was too late and they told me it wasn't worth the trouble. Years later the detective informed me that he was in prison in another state for assaulting someone else and I still feel guilty about it. I've had a difficult time finding good relationships, and up until now found myself in a few abusive relationships, which leads to my other stalker.
The other was my ex-boyfriend. After we broke up, I left him because I found out he had two other girlfriends at the same time, he continued to follow me. He would park outside of my new boyfriend's house and follow us around. This was like a year after we broke up. I tried to talk to one of his girlfriends I used to be friends with, which proved to be difficult because he would go through and delete her emails so she didn't even find out till another year later. He was tech savvy and would constantly hack my Facebook/email and other things and send stuff pretending to be me trying to get my current boyfriend to break things off. His other girlfriend and I ended up telling on him to his family, because he was lying to them too. He left me alone after that.
It's been difficult for me to connect with people. I'm working on doing better now. I've had a lot of therapy and I am in a healthy, happy relationship now. This was years ago (2005, 2008), but I am still working on recovering. I am still very jumpy and always on the defense. Whenever I go anywhere alone, I am prepared for any attack. I don't let many people into my life and I don't have many friends aside from a few close ones. It's just how I live my life.