A synonym that starts with s for self centered?

Nouns include egotist or narcissist. The adjectives would be egotistic, narcissistic, self-absorbed, or selfish. Basically a person like this will be always be alone, insecure, and unhappy with their life, unless they change. Usually friends, family and others find a person like this to be annoying and weak, if all they do is talk about themselves constantly.