Other forms: egomaniacs
An egomaniac is a person who's obsessively self-absorbed. An egomaniac might only take photos of himself — never of another person.
Just because you like to take selfies doesn't make you an egomaniac — a true egomaniac has a psychological disorder that makes him believe that he is the greatest, most important person in the world. You can also use the word to describe someone you know who's a self-centered jerk, though. Egomaniac, coined in the early 19th century, combines ego, "the self," or in Latin, I, and maniac, from the Greek mania, "madness or frenzy."