A complex character can be called many things. Believable and realistic are two words, but perhaps you are thinking of "round" characters as opposed to "flat" characters who are not complex.
Round
A word character means a character that has many meaning to it. Example: Goofy is silly. SILLY is the word that describes or has that meaning to a character.
Antagonist. Tormentor.
individual
static minor character
Holy order
Eponymous
dynamic
Brave
out going and helpful.
Nova net:: Individual
The word most is an adjective. It describes a noun.