I have had this come up several times, mostly from women with violent and/or stalking significant others. I refer them to a retired cop friend or the range master at my local range. Usually they recommend people without a lot of firearms experience get a a snub nosed revolver in .38 Special. They are small and concealable yet can do the job at close range. Get a snub-nose .38 revolver ...Smith and Wesson. (Model 642...... concealed hammer so it will not snag in your clothes... and its lightweight... and can be pocket carried.) I am a retired LEO. 31 years on the job. Almost all of it as a firearms instructor. A snub-nose would be the last gun I would advise a new shooter to buy. They are difficult to learn to shoot well due to their light weight (more recoil) and short sight radius.