Without reading the articles that CANDC posted, I can confirm that there is a such thing as a covert narcissist and I'm likely a mild example of one myself.

I can be considerate, polite, or even humble, but in my mind, I'm better than most people both because I have a high IQ, and because I've had to endure abuse most of my life which makes me tougher and more resilient than most people. Often times, I call myself a demigod and use titles in many of my online aliases such as "Lord" or "Archon". Furthermore, I often wear a mask and lie and manipulate most people for my own self protection and if anybody dares try to expose my charade or call me out on my B.S, I push them out of my life.

This type of thinking doesn't hold me back in my life aside from romantic relationships (which I ruin due to a chronic fear and discomfort with closeness) and I can even make friends easily, but it takes years to earn my trust enough for me to reveal the "real" me which is fine because I like my circle small anyways.

In short, these types are more common than you might think and narcissism can manifest itself in more subtle ways.