Domnitor was the official title of the ruler of Romania between 1859 and 1881.

It was used officially only after Wallachia and Moldavia chose the same ruler in 1859. Before that the Wallachian and Moldavian rulers had the title of voivode, although unofficially they were known as domnitors. The word itself is derived from the Romanian "domn" (lord), from Latin "Dominus".

There were only two domnitors of Romania:

• Alexandru Ioan Cuza (1859 - 1866)
• Carol I of Romania (1866 - 1881)

In 1881, Carol was crowned as King of Romania.