invader
Definitions
A person or group that enters a country, region, or place by force in order to conquer or occupy it.
An organism that spreads into an area where it is not native and has a harmful effect on the local environment.
Examples
The castle guards were alerted to the presence of an invader in the courtyard.
The invasive species acted as an invader, quickly destroying the native plants in the garden.
Synonyms
intruder aggressor raider trespasser occupier infiltrator attacker