Yeah, and mercenaries too, but more of a strategic one, not tactical as a modern one.
Some of them worked as "客卿" (persons who came from a foreign kingdom/principality but listed as a high-ranking official in the host kingdom/principality) and helped the king/prince with reforms. Local aristocracies were usually the target of reforms (in that sense, very much like a consultant of today) so someone from outside needs to move it forward. Some can serve as generals who own a small number of elite soldiers and can lead armies for the king/prince of the host kingdom/principality.
I'm pretty sure you can find similar examples in Medieval Europe.
Early consultants?