Ur-Baba or Ur-Bau (Sumerian: 𒌨𒀭𒁀𒌑 ur-Dba.ba6 or ur-Dba.U2, servant of the goddess Bau; died c. 2144 BC) was ensi of Lagash from 2093 BC – 2080 BC (short chronology) or 2157 BC – 2144 BC (middle chronology), roughly contemporaneous with the last king of Akkad, Shu-turul. In one of his inscriptions, he refers to himself as a child of the god Ninagal (Sumerian: 𒀭𒎏𒀉𒃲).

According to inscriptions of Ur-Baba, during his reign, Lagash enjoyed prosperity and independence from the Akkadians. His daughter Ninalla married Gudea, who succeeded him as ensi.