Hi,
Not quite. The term god complex is pop psychology. It does not appear in any of the clinical books or the DSM V. In essence god complex refers to people who have an unshakeable self belief / feeling of self worth. They often believe they are right in the face of overwhelming evidence to the contrary. They have no doubt about their decisions. And they have a belief in their own worth that places them above that of other mortals. They do not consider themselves gods or like gods.
They by and large won't make good villains though. Because while some - not all - will feel so entitled that the worth of others may not mean much to them and thus will be sacrificeable, the complex itself is self destructive. Being incapable of accepting that you could be wrong, makes it impossible for someone to see their faults and correct them. Thus they are not able to adapt and improve as most people can. And as far as their great plans go, since they are in their own minds incapable of being wrong, they are incapable of seeing that their plans are going wrong or prepare for that eventuality. These are not the masterminds. Rather they are the self deluded fools who often do completely inexplicable things.
In classic literature Captain Nemo would be the person that most would think of having a god complex. But in actual fact he is mad but can accept that things won't necessarily go his way and prepare for that eventuality. Dr. Moreau is more fitting, because he is incapable of seeing the flaws in his creations even when they kill him. And Narcissus - Narcissistic Personality Disorder - sort of fits because he was so in love with his own reflection (essentially an aspect of himself - his beauty) that he fell into the lake and drowned.
Cheers, Greg.