raider

Short definition from Wiktionary

Noun

1. 1
   One who engages in a raid; a plunderer.
2. 2
   A person who takes or attempts to take control of a firm against the will of current management by purchasing a controlling interest of stock and acquiring proxies.
3. 3
   A special forces operative; a commando.
4. 4
   A warship which is light, maneuverable, and fast-moving.
5. 5
   A warplane on an air raid.
6. 6
   A law enforcement official who conducts a raid on a building in search for illicit goods.
7. 7
   A person who uncovers evidence of improper behavior within governmental or private organizations.

Proper noun

1. 1
   A surname from German.