There are many different ways to deal with a stalker. If the stalker is someone that you know, whether an ex-boyfriend or an obsessed ex-husband, the first thing you need to do is inform all your friends and family members so they won't be fooled by some sob story. Many stalkers will use your friends and family members as sources of information. Secondly, if you consider this person a serious threat you must file a restraining order against him, then you must change your phone number and leave strict instructions to friends and family members to never give out your number under any circumstances.
If you are been stalked by a stranger, whether the creepy guy or girl from the laundromat around the corner or the creep from the grocery store, it is essential for your safety that you have a locksmith come over to your place of residence and change the locks on your door. Put on double or triple bolts if necessary, and also secure your windows with bars on both the inside and outside of the window.
The most important thing to remember if you have a stalker is to be safe. The safest thing to do, especially if that person knows where you reside, is to move; although it might be extremely inconvenient for you, if that person is violent and dangerous you need to either move out of the town where you live, or if it is a small town you need to possibly move to another state.
Experience has shown there are two different types of stalkers, the stalker that follows you because he or she likes you and is afraid to approach you - so they follow you thinking it's harmless; and someone with whom you've previously had a relationship (not necessarily sexual). This type of stalker has likely been rejected and feels slighted, so they may break into your apartment, follow you to work, 'accidentally' run into you at the store or elsewhere, or try other methods to ease themselves back into your life.
When dealing with a stalker it is best to remember that a stalker is never harmless. Think about the time and energy it takes to stalk someone, to follow them every waking moment: that is obsession and is extremely dangerous when someone is so consumed with another person. Stalking can lead to property damage, injury, and, in extreme cases, loss of life.
It is vital, when dealing with a stalker, to always report it to the police; for your safety and peace of mind it might also help to take some self-defense classes.