A single, hundred strong company of Space Marines can defeat an army a hundred times its size, bring a rebellious world back under Imperial rule or besiege an entire alien city. Such is their skill in the field of war that there is little that they can not achieve.
The enemies of the Imperium fear many things, they fear discovery, defeat and death. But most of all they fear the wrath of the Space Marines!
— Imperial Proverb;
A Fortress will not stop the Space Marines, although it may slow them down.
— Imperial Proverb
The Arms and Armor of a Space Marine are not his greatest weapons, though they are terrible things indeed: Relics of the insane times of the Dark Age of Technology.
Neither are the changes wrought upon his body and mind, though he is made stronger, faster and smarter than any mere human.
No, it is the his Faith that makes the Space Marine such a terrible foe. Purpose of will unlike any seen in Xeno or Men, He knows no doubt or fear, never shall he waver from the destruction of his enemies. Remember: all the guns in creation are worthless without the will to pull the trigger.
War is the only place where we can be complete. Battle can be the only activity where excellence can be meaningful. Do not believe that you can be scholar, a philosopher, or a leader of men. You are a warrior. When you are not inflicting death, you are not justifying your life.
— Daenyathos - "War Incarnate"
Give me a hundred Space Marines. Or failing that, a thousand other troops.
— Rogal Dorn, prior to the storming of the Lucid Palace
Soldiers? I hardly think they fit that description. Do you know how they make them, Threlnan? No, of course you don't. They find some barbaric planet where children fight before they can walk, and they hunt down the most bloodthirsty killers. They recruit them when they're twelve, thirteen, fourteen, with all that hate and that arrogance, just at the age when you think you're bulletproof and nothing can kill you. Then they keep them like that, give them a gun and some armour, and point them at the nearest enemy. They're not soldiers, colonel, they're maniacs. They won't answer to anyone save their own kind. And have you seen how they fight? They find the closest enemy and try to cut them up with swords. Madness. Just madness. Just so there can be something to carve on the cathedrals and put in children's stories. Now I've got a hundred of them just waiting to bend all my battle-plans out of shape.
— Lord General Xarius on Space Marines
General Ross: You're aware that we've got an infantry weapons development program. Well, in WWII they initiated a sub-program for bio-tech force enhancement.
Emil Blonsky: Yeah, a Super Soldier.
General Ross: Yes. An oversimplification, but yes... Across the hall they're trying to arm you better? We're trying to make you better.
—Film/The Incredible Hulk
"You have been called upon to serve, you will be trained... and you will become the best we can make of you. You will be the protectors of Earth and all her colonies."
— Dr. Catherine Halsey, Halo: The Fall of Reach
"But here's the thing - creating supersoldiers doesn't make the slightest bit of rational sense. First of all, you're basically creating an entity whose only purpose is to fight, so what the hell are you going to do with them during peace time, pack them in a box? And this is assuming you could even control them. If they haven't regressed to a slavering bestial state or been driven insane by the monstrosity they have become, how are you going to make them do your bidding, Mr. Small Fragile Human General? You really want to start issuing threats that might come back to haunt you when some leashes get slipped? To say nothing of the fact that the ethical lapse involved would be ruinous in a country where people fight for the rights of embryonic cell clusters, and that most supersoldiers could be effectively countered by, say, dropping a great big bomb. "
— Ben "Yahtzee" Crowshaw on some of the inherent logical flaws involved in this trope.
"The earlier projects sought to alter their subjects biologically using radioactive chemicals. First was PROJECT: ARES. Of 104 volunteers, Captain Jansen was the only subject who survived ... intact."
— Dr. Kate Smallwood, The Specialists Page 89
"In the 1960s, with war in Asia looming, The US began research into Operation Black Tower; what we've now come to call the Universal Soldier Program. A high-response, self-sustaining, quick-healing, stronger, faster soldier; fueled by high-concentrate nutritional supplements, a soldier that operates without conscience, or hesitation. By freezing a Human body with nitrogen-based gas, repairing it and reheating it through pituitary and thyroid augmentations, We were able to revive a recently deceased soldier, and in the process, improve them. Programmable and erasable. One that you could turn on, and one that you could turn off."
—Dr. Richard Porter, Universal Soldier: Regeneration
"Once again, Spartans do in twenty-four minutes what Marines can't do in twenty-four hours."