George Brett in 1993. That was the last time that someone spent their entire career with the Kansas City Royals. It has been 22 years and counting since a player began and ended their career with the Royals organization, remaining in Kansas City exclusively for the duration of their career. That is far too long of a time.
Of course, there are mitigating circumstances for that drought. The Royals went through quite a stretch of time without any true leadership after Ewing Kauffman passed, and the team pared down their payroll to the point where anyone making even the slightest amount of money was sent away.