gestor

listen to the pronunciation of gestor
İspanyolca - İngilizce
manager
managing, having a tendency to manage or control
business agent
promoter
İngilizce - İngilizce
a manager of another's affairs

We may add that, if a man has managed my affairs with no thought of me, but for the sake of gain to himself, then, as we are told by Labeo, he managed his own affairs rather than mine (and, no doubt, a man who intervenes with a predatory object aims at his own profit and not at my advantage); but nonetheless, indeed all the more, will such a one too be liable to the action on negotia gesta. Should he himself have gone to any expense in connection with my affairs, he will have a right of action against me, not to the extent to which he is out of pocket, seeing that he meddled in my business without authority, but to the extent to which I am enriched.

a manager of anothers affairs