The space marine is an archetype of military science fiction describing a kind of soldier who operates in outer space or on alien worlds. Historical marines fulfill multiple roles: ship defence, boarding actions, landing parties, and general-purpose high-mobility land deployments that operate within a fixed distance of shore or ship. By analogy, hypothetical space marines would defend allied spaceships, board enemy ships, land on planets and moons, and satisfy rapid-deployment needs throughout space.

Alfred Johannes Olsen, better known under his pen name Bob Olsen, was an American science fiction writer.