“This site contains lists of heads of state and heads of government (and, in certain cases, de facto leaders not occupying either of those formal positions) of all countries and territories, going back to about 1700 in most cases. Also included are the subdivisions of various countries (the links are at the bottom of the respective country entries), as well as a selection of international organizations. Recent foreign ministers of all countries are listed separately.
In cases where not even the exact year of the beginning or end of a ruler’s term is known, the asterisk (*) is used to indicate dates at which the person is known to have been in office, e.g., *1924 – 1925* means the term began in 1924 or earlier and ended in 1925 or later. All dates are New Style (Gregorian). (f) indicates female rulers. Birth and death years are also provided (b. = born, d. = died, s.a. = see above), but note that the given birth years may be questionable, as different sources often give contradictory information. In cases where it is particularly unclear, the birth year is followed by a question mark (e.g., 1923?) but that does not mean that the year is guaranteed to be correct when there is no question mark. Also, when no death year is given, it should not be taken for granted that the person is indeed still alive.”
See on www.rulers.org