A "mercenary" is a person who fights in wars or performs dangerous jobs in exchange for money, rather than for a specific cause or belief. Full definition
But the league is subjected to a sudden deadly attack by a well drilled group of mercenaries of unknown clients. (sbs.com.au)
I sat down to play an evening of Mercenary Kings with the other two members of the Short Pause triumvirate, and we spent more time trying to start a game than we did actually playing one. (shortpause.com)
Thankfully the game does a decent job of integrating the other players when in dungeons by describing them as mercenaries who will help you on your quest. (igcritic.com)