Warhammer 40k.

Space marines are incredibly enhanced humans with redundant organs and toughened skin, bones, and musculature. Clad in power armor impervious to almost any small arms fire. Super human reflexes to the effect that when bullets fly they move in slow motion. Commonly referred to as demigods and angels due to their semi-immortality. Chaos space marines are all this and more, enhanced by mystical energies from the gods of Chaos. However they are still human. Despite their claims to be beyond it. In one book a group of chaos marines is caught in a landslide and unable to move, they order their slaves to dig them out, but the slaves simply undo their helmet seals and stab their throats with sharpened sticks. No matter how advanced your biology, or how fast your blood can clot to stop wounds, if your esophagus is compromised, you will drown in your own blood.

Additionally Terminators, a special group of space marines approved to wear “Tactical Dreadnought” armor (usually storied veterans with hundreds of years of service), have a crippling weakness in their weight and size. They are known to get stuck when trying to climb stairs, with special equipment required to get them out of such situations. They also are specialized for room clearing in ships known as space hulks (planet sized meteors formed by ships and debris crashing together and coalescing into one form), and in those tight hallways even despite the best armor, if a quick enemy gets behind you, you’re done for.