1) Assailant 2) Attacker 3) Encroacher 4) Raider 5) Thief 1) Attila, most of the time 2) Conqueror, often 3) Encroacher 4) Encroaching army 5) Hannibal was one 6) Interloper 7) Intruder 8) Napoleon, to a Russian 9) Raid participant 10) Saxon or Celt, once 11) Trespasser 12) Unwelcome arrival 13) Villainous Venusian 
It was launched into orbit by a H-IIA launch vehicle on 27 February 2014 as a sub-payload of GPM Core satellite. It reentered to Earth atmosphere on 2 September 2014. ...
• (n.) One who invades; an assailant; an encroacher; an intruder.
In·vad'er noun One who invades; an assailant; an encroacher; an intruder. 
[n] - someone who enters by force in order to conquer
Plant species that were absent in undisturbed portions of the original vegetation of a specific range site and will invade or increase following disturbance or continued heavy grazing.