Zarpanitu (also romanized as Ṣarpānītu) was a Mesopotamian goddess regarded as the spouse of Marduk. Not much is known about her character, though late sources indicate that she was associated with pregnancy and that she could be assigned similar roles as her husband, including that of queen of the gods. She was originally worshiped in Zarpan, a village near Babylon, though the latter city itself also served as her cult center.

The most common spelling of Zarpanitu's name in cuneiform was ^dzar-pa-ni-tum. It is romanized as Ṣarpānītu instead by Jeremy Black and Anthony Green, but this choice has been criticized by Wilfred G. Lambert, who points out that while cuneiform does not differentiate between the sounds z and ṣ, supplementary evidence for the former option is provided both by various scholarly etymologies of the name and by texts written in the Aramaic alphabet, which does differentiate between z and ṣ. The Aramaic spelling zrpnt is known from the Sefire inscriptions. Authors such as Paul-Alain Beaulieu, Andrew R. George, Joan Goodnick Westenholz and Takayoshi Oshima (who was responsible for the relevant entry in the Reallexikon der Assyriologie) also favor romanizing the name with a z. However, romanizations starting with ṣ also continue to be used in Assyriological literature.

Zarpanitu's name has Akkadian origin. Two different possible etymologies are well documented in primary sources, "the lady of the city of Zarpan" and "creatress of seed" (from zēr-bānītu). Today it is assumed the name was most likely derived from the toponym Zarpan, a settlement located near Babylon, though seemingly according to a folk etymology it was named after the goddess instead, as attested in a myth known only from a fragmentary tablet from the library of Ashurbanipal. While attempts have been made to etymologize the name as "silvery" instead, this view is now regarded as unsubstantiated.

Two names which originally designated the spouse of Asalluhi, Erua and Papnunanki, came to be used as names of Zarpanitu after her husband Marduk was equated with that god in the eighteenth century BCE. However, this tradition is not yet documented in the Old Babylonian forerunner to the later god list An = Anum, where both of these names are stated to refer to the same goddess, but without identification with Zarpanitu. The theonym Erua could be used either as a sumerogram meant to be read as Zarpanitu or as an epithet, while Papnunanki typically appears in place of her standard name. An early case has been identified in a text from the reign of Samsu-Ditana, who in a formula written in Sumerian refers to Zarpanitu as Papnunanki, in contrast with his predecessors Sumu-la-El, Hammurabi and Samsu-iluna, who all used her primary name in texts written in this language.

According to a god list, secondary names of Zarpanitu were Elagu and Laḫamun, glossed as used in Elam and Dilmun, respectively. However, it has already been pointed out by Friedrich Wilhelm König [de] in the 1930s that Elagu appears exclusively in Mesopotamian, as opposed to Elamite, texts. The second name, while sometimes quoted among Dilmunite theonyms in Assyriological literature as recently as in the 1990s, is similarly known only from sources from Mesopotamia.

Not much is known about Zarpanitu's character. Joan Goodnick Westenholz has suggested that she and Tashmetum were simply "prototypical divine wives". In late sources she could be characterized as a motherly figure connected to birth. She was worshiped under the byname Erua as a goddess associated with pregnancy.

In the first millennium BCE, Zarpanitu's role as the wife of Marduk made her a high ranking deity, which was reflected in the epithets applied to her, such as bēlet ("lady"), bēltīya ("my lady"), šarratu ("queen"), bēlet Bābili ("lady of Babylon"), šarrat Bābili ("queen of Babylon"), bēlet Esagil ("lady of Esagil") or šarrat Esagil ("queen of Esagil"). In some cases, she was effectively portrayed as Marduk's feminine counterpart, with similar characteristics, including a connection to divination, and analogous position in the pantheon, that of queen of the gods. The so-called Archive of Mystic Heptads calls her the "mistress-of-the-goddesses" (^dbe-let-i-la-a-ti), which presumably reflects her status as the foremost female deity in late Babylonian theology. At the same time, she was not included in royal statements of rulers acknowledging their dependence on Marduk.

Zarpanitu's status as the spouse Marduk is seemingly already indicated by a reference to these two deities in a year name of Samsuiluna. The tradition of pairing them with each other might have originated as early as in the third millennium BCE, and they already appear next to each other in the Weidner god list. Other texts belonging to this genre also pair them together, with the exception of Old Babylonian god lists from Nippur, which do not allude to any relationship between them. Zarpanit is instead placed in the section which otherwise lists deities related to Inanna in this case, which according to Joan Goodnick Westenholz is unusual for her. It was believed that Zarpanitu could intercede with Marduk on behalf of petitioners, though Céline Debourse remarks that texts documenting this function could portray her in an ambivalent light, as she could both slander and praise these who asked her to mediate on their behalf, which can be considered a parallel to Marduk being portrayed both as a forgiving and punishing figure himself. Due to being regarded as the wife of Marduk, Zarpanit was also considered the daughter-in-law of Ea.