Nanite Warhead

A type of defensive warhead that can be summed up as massively improved, hightech version of Corrosive Warhead. Rather than unreliable chemical compounds, it employs advanced nanotechnology.
It is essentially a lot of nanites programmed to eat and reproduce, packed and compressed into the warhead. If even a single nanobot lands on a missile coming through its cloud, it will inadvertedly devour it. Rarely they will manage to eat entire warhead unless the nanobots have a lot of time or are supertech in origin, but it will cause a lot of damage, sometimes making them break midflight, break its guidance system, propulsion etc.
It is often used but almost exclusively by capital ships. They have a lot of missile launchers, so can construct rather dense and widespread nanite clouds, causing a lot of damage to any salvo coming through it.