Šū-Nīnua was the fifty-fourth ruler of Aššur according to the Assyrian King List [/riao/kinglists/assyriankinglist/index.html] (AKL). His unusual name means "one from Nineveh" (Michel 2011-13, 315) and J. Reade (2001, 8) suggests that he may have been a governor of Nineveh. No royal inscriptions of his are presently known. According to the AKL, Šū-Nīnua was the son of Bāzāyu (the fifty-second ruler) and he succeeded Lullāyu, a "son of a nobody" who may or may not have been a usurper. A different king list, fragment VAT 9812 [/riao/kinglists/fragmentvat9812/index.html], omits the thirteen names listed prior to Šū-Nīnua in the better preserved copies of the AKL and places Šū-Nīnua's name immediately after a horizontal line, possibly indicating that the period before his reign was one of confusion and that he refounded the Bēlu-bāni dynastic line (Yamada 1994, 27).
According to the AKL, two of Šū-Nīnua's sons succeeded him to the throne: first Šarma-Adad II and then Erišum III. However, Reade (2001, 8) proposes that Šarma-Adad I and Šarma-Adad II are the same person. If this is the case, then Šarma-Adad II could not have been Šū-Nīnua's son. Šū-Nīnua may also have had a son named Išmē-Dagān who did not rule as king and that man may have been the father of Šamšī-Adad III, who the AKL records was the son of an Išmē-Dagān who was the son of Šū-Nīnua and the brother of Šarma-Adad II; the identity of Šamšī-Adad III's father is debated (see the introduction to that monarch's reign).
Poppy Tushingham & Jamie Novotny
Poppy Tushingham & Jamie Novotny, 'Šū-Nīnua (or Kidin-Nīnua)', RIA 1: Inscriptions from the Origins of Assyria to Arik-dīn-ili, The RIA Project, 2023 [http://oracc.org/oldassyrianperiod/belubanidynasty/shuninuaorkidinninua/]