Dispositor. From the word dispose. The dispositor disposes the planets under its rulership.
The ruled are "at the disposition of" the ruler. He may do with them as he pleases.
The chart then takes on the tonality of the final dispositor. Where Mars, for example, is final dispositor you will find a warrior. Bruce Lee is one example; another is Martin Luther, the 16th century priest who defied the Pope and brought about the Reformation.