The Vatatzes or Batatzes (Greek: Βατάτζης) family was a noble Byzantine family of the 11th–14th centuries with several branches, which produced several senior generals of the Byzantine army and, after John III Doukas Vatatzes intermarried with the Laskaris, the ruling line of the Empire of Nicaea until the usurpation of Michael VIII Palaiologos in 1261. The feminine form of the name is Vatatzina (Βατατζίνα).
According to the Greek scholar Konstantinos Amantos, the name Βατάτζης is a diminutive form of βάτος, "bramble, briar", and suggests that it was given as a nickname signifying a harsh character. Another possible origin is βατάκι, "ray fish".
The first member of the family, known simply by his surname, is attested around the year 1000. John Skylitzes (Synopsis Historion, 343.134) records that "Vatatzes with his entire family" was among those "distinguished citizens of Adrianople" who fled to the Bulgarian emperor Samuel because they were accused of pro-Bulgarian sentiments. Over the next centuries, the family remained associated with Adrianople and the surrounding region (the thema of Macedonia), where their estates were. Likewise the 13th-century chronicler Ephraim the Monk mentions Didymoteichon/Orestias as the family's native city.
Michael Psellos records that in 1047, a John Vatatzes, relative of Emperor Constantine IX Monomachos (r. 1042–1055), joined the revolt of Leo Tornikios. The family became prominent in the 12th century, when several members rose to high offices. Theodore Vatatzes married Eudokia, the sister of Emperor Manuel I Komnenos (r. 1143–1180) and was named despotes; his sons were Andronikos, Alexios, and John Komnenos Vatatzes, who became megas domestikos (commander-in-chief of the Byzantine army). The hagiographer of the Nicaean emperor John III Doukas Vatatzes (r. 1221/22–1254), identified John with the latter's grandfather, who supposedly had two sons named Nikephoros and Theodore, who were persecuted by Andronikos I Komnenos (r. 1182–1185. According to Niketas Choniates, however, John's sons were named Manuel and Alexios. This is most likely the result of a confusion by the hagiographer.