Principe Domnitor (Romanian pl. Principi Domnitori) was the official title of the ruler of Romania between 1862 and 1881. It was usually translated as "prince regnant" in other languages and less often as "grand duke". "Domnitor" is an adjective derived from the Romanian word "domn" (lord or ruler) and, in turn, from the Latin "Dominus". The title Domn had been in use since the Middle Ages and it is also the Romanian equivalent to the Slavic Hospodar. Moldavian and Wallachian rulers had used this term for their title of authority as the head of state, while "voievod" represented the military rank as the head of the army.

The title acquired an officially recognized meaning after Moldavia and Wallachia united to form the Romanian United Principalities under Alexander John I, who had become the ruler of both states since 1859. Alexander John abdicated in 1866 and was succeeded by Carol I, who promulgated the first constitution who officially used the name Romania for the country. He held the title until 1881. When Romania was proclaimed a kingdom in March 1881, Carol became its first king.^[1]

This is a graphical lifespan timeline of Domnitors of Romania. The domnitors are listed in order of office.

• King of the Romanians
• List of rulers of Moldavia
• List of rulers of Wallachia
• List of heads of state of Romania