According to the ancient commentaries, Iliad 21.195 was omitted by some sources, thereby making Acheloios, instead of Ocean, the origin of all waters, including the sea: the reasons for and the date of such a version of the text have been debated. In this paper I argue that the version without line 195 actually represents the earlier textual stage. This role of Acheloios is paralleled in the poem interpreted in the Derveni papyrus, and some features of Acheloios' cosmological function, as well as his iconography, find interesting parallels in the Near East. As a 'cosmic' figure, Acheloios was in competition with Ocean, and is only rarely so represented in later preserved texts. His function as the origin of all fresh water and the source of all springs was more persistent, probably due also to his cultic role in Dodona: this, too, is probably reflected in another ancient variant for the text of Il. 16.234