raider

noun7

1. •
   One who engages in a raid; a plunderer.
2. •
   A special forces operative; a commando.
3. •
   A warship which is light, maneuverable, and fast-moving.
4. •
   A warplane on an air raid.

   • It was attacked by an evening raider while pulling a passenger train in a south-east coast area. — 1943
5. •
   A law enforcement official who conducts a raid on a building in search for illicit goods.
6. •
   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.
7. •
   (informal) A person who uncovers evidence of improper behavior within governmental or private organizations.