megalomaniac

As an adjective complacent

is uncritically satisfied with oneself or one's achievements; smug.

As a noun megalomaniac is

one affected with or exhibiting megalomania.

As nouns the difference between megalomaniac and maniac

is that megalomaniac is one affected with or exhibiting megalomania while maniac is an insane person, especially one who suffers from a mania.

As a noun megalomaniac

is one affected with or exhibiting megalomania.

As an adjective egotistic is

egotistical.

As nouns the difference between megalomaniac and paranoid

is that megalomaniac is one affected with or exhibiting megalomania while paranoid is someone suffering from paranoia.

As an adjective paranoid is

of, related to, or suffering from paranoia.

As nouns the difference between narcissistic and megalomaniac

is that narcissistic is a narcissist while megalomaniac is one affected with or exhibiting megalomania.

As an adjective narcissistic

is having an inflated idea of one's own importance.

As nouns the difference between egomaniac and megalomaniac

is that egomaniac is a person obsessed with their own (supposed) importance while megalomaniac is one affected with or exhibiting megalomania.

As nouns the difference between demagogue and megalomaniac

is that demagogue is demagogue while megalomaniac is one affected with or exhibiting megalomania.

As an adjective demagogue

is demagogic.

As a noun megalomaniac

is one affected with or exhibiting megalomania.

As an adjective megalomanic is

afflicted by megalomania.

As nouns the difference between megalomanias and megalomaniac

is that megalomanias is plural of megalomania while megalomaniac is one affected with or exhibiting megalomania.