Josif Rajačić, also known as Josif Rajačić-Brinski, was a metropolitan of Sremski Karlovci, Serbian Patriarch, administrator of Vojvodina, and baron.

The Metropolitanate of Karlovci was a metropolitanate of the Eastern Orthodox Church that existed in the Habsburg monarchy between 1708 and 1848. Between 1708 and 1713, it was known as the Metropolitanate of Krušedol, and between 1713 and 1848, as the Metropolitanate of Karlovci. In 1848, it was elevated to the Patriarchate of Karlovci, which existed until 1920, when it was merged with the Metropolitanate of Belgrade and other Eastern Orthodox jurisdictions in the newly established Kingdom of Serbs, Croats and Slovenes to form the Serbian Orthodox Church.