Iago? Complex? His entire motivation is jealousy of Othello, and for that he wrecks everyone's shit while basically admitting "I do it because I'm a complete bastard." He is cartoonishly evil.
I see i was not the first to come up with this.
As soon as i read it i was like 'Seriously? Iago? he's not any more complex than villians i've seen in games'
He's got a bunch of hinted at motives, and all of them are quite stereotypical/cliche.
Jealousy, revenge, paranoia, being a prick.
(Somewhat simplified, but i can't be bothered listing them all seperately, 'he suspected othello sex'd his wife' 'he was angry at being denied promotion', etc. They all fall into the above categories so i'll just leave it at that.)