Male Lead (Hero):
The nephew of the Scientist; he is a clean-cut college student who rescues the Heroine from the centipede when it attacks the subway station. Good, upstanding all-american role model, etc.
Works as secretary to the Scientist; she is at the subway when it is attacked by the Centipede, and is rescued by the Hero. Basic damsel-in-distress archetype - says very little, screams instead of turning and running, etc. Acts as love interest for Hero.
Generic expert in "Science"; is person who explains the origins of the giant Centipede and realises that the military's attacks are causing it to grow faster. Tries to get the military to call of its attacks before it is too late, and also comes up with the eventual solution.
Gung-ho military stereotype; believes in shooting first and asking questions later. Ignores the warning from the Scientist, due to arrogance and unquestioning belief in the superiority of the US military.