I know this has been said a zillion times in this thread alone, but Marcus wasn't motivated by revenge. He ordered the murder of Khan (and sabotaged the Enterprise) to start a war with the Klingons. He then tried to destroy the Enterprise himself when this plan failed, to cover his tracks. His motivation there wasn't revenge -- it was self-preservation.
Kirk, Spock, and Khan were. Khan was the antagonist, not Marcus.