Ajtony, Ahtum or Achtum (Hungarian: Ajtony, Bulgarian: Охтум, Romanian: Ahtum, Serbian: Ахтум) was an early-11th-century ruler in the territory now known as Banat in present Romania and Serbia. His primary source is the Long Life of Saint Gerard, a 14th-century hagiography. Ajtony was a powerful ruler who owned many horses, cattle and sheep and was baptised according to the Orthodox rite in Vidin. He taxed salt which was transferred to King Stephen I of Hungary on the Mureș River. The king sent Csanád, Ajtony's former commander-in-chief, against him at the head of a large army. Csanád defeated and killed Ajtony, occupying his realm. In the territory, at least one county and a Roman Catholic diocese were established.