His Excellency

English

(formal) A title of respect for males used when referring to heads of state, heads of government, governors, ambassadors, ecclesiastics such as Catholic Bishops, Nuncios, royalty and those of equivalent rank.

This is the third-person form of address. The form used in the second person is Your Excellency.
Those addressed as Excellency are heads of state other than monarchs, heads of government, governors, ambassadors, ecclesiastics such as Catholic Bishops, Nuncios etc, royalty, and others holding equivalent rank (e.g., heads of international organizations, high commissioners in the Commonwealth of Nations) and the FIFA President.
The exact forms of address vary somewhat from country to country.

title of respect