Wer (Wēr), also known as Mer, Ber and Iluwer was a weather god worshiped in parts of Mesopotamia and ancient Syria.

It is presumed that he was originally one of the main deities of the northern parts of these areas, but his cult declined in the second half of the second millennium BCE.

"[3] The spelling Mēr was consistently employed in texts from Mari and nearby areas, with the chronologically most recent example being the theophoric name Tukulti-Mēr (a contemporary of Ashur-bel-kala[4]) from the late second millennium BCE, while Wer (Wēr) was the form used in southern Mesopotamia between the beginning of the period of the Third Dynasty of Ur end of the reign of the First Dynasty of Babylon, as well as in Old Assyrian sources contemporary with the texts from Kanesh.

[5] Whether dME-RU, possibly to be read as Meru, attested in sources from the Early Dynastic period (including the Abu Salabikh god list)[6] is the same deity as Wer is uncertain.

[2] According to Wilfred G. Lambert, available sources might indicate that he was originally one of the main gods worshiped in northern Mesopotamia, but eventually declined in the middle of the second millennium BCE due to loss of his cult sites.

[13] A number of Assyriologists, including Dietz Otto Edzard,[14] Wilfred G. Lambert[5] and Andrew R. George, assume that Wer was the same deity as Itūr-Mēr,[15] the tutelary god of Mari,[16] but this view is regarded as unsubstantiated by Daniel Schwemer[17] and Ichiro Nakata, who point out that the latter deity's name is an ordinary theophoric name ("Mēr has turned [to me]"[3]) and that for this reason he is more likely to be a deified hero venerated as part of an ancestor cult tied to a specific location.

[21] While known copies of a single passage from the incantation series Šurpu alternate between Wer and a deity named Immeriya, it cannot be established if the latter, who is otherwise best known from an inscribed statue possibly taken as bounty by Untash-Napirisha, was related to him in any way.

[10] While confirmed attestations go back to the time of the Akkadian Empire, only from the Old Babylonian period onward the god is known from sources other than theophoric names.

[32] Andrew R. George assumes that while the mountain belongs to Wer, and he appointed Humbaba as its guardian and his second in command, the decision still had to be approved by Enlil.