Mercenary Ninja

A is a skilled ninja who is hired to fight for another country other than his own in lieu of money. Before the founding of shinobi villages, the majority of the clans in existence at that point were mercenary military forces for hire by whomever.

Trivia

 * When Zabuza Momochi and Haku defected from Kirigakure, they became mercenaries for hire.
 * Akatsuki is a mercenary group.
 * In Shippūden episode 233 a group of mercenary ninja believed Naruto Uzumaki to be a missing-nin and tried to capture him for bounty they assumed was on his head.