Aššur-nādin-aḫḫē I, son of Aššur-rabi I was the sixty-sixth ruler of Assyria, according to the Assyrian King List [/riao/KingLists/AssyrianKingList/AssyrianKingList/index.html#Mittani] (AKL). Unfortunately, the length of his reign is not known as it is either damaged or missing in the extant copies of the AKL (Nassouhi [/riao/KingLists/AssyrianKingList/NassouhiList/index.html], Khorsabad [/riao/KingLists/AssyrianKingList/KhorsabadList/index.html], and SDAS [/riao/KingLists/AssyrianKingList/SDASList/index.html]), which records that his brother Enlil-nāṣir II deposed him.
Two fragmentary inscriptions are written in the name of a Aššur-nādin-aḫḫē, but it is uncertain whether these should be ascribed to the first or second Assyrian king of that name; scholars generally assign them to Aššur-nādin-aḫḫē II (Grayson, RIMA 1, p. 105). There is a slight possibility that Aššur-nādin-aḫḫē I is referred to in a letter of Assur-uballiṭ I from El Amarna (Rainey 2015:130 letter 16) where an Aššur-nādin-aḫḫē is credited with initiating diplomatic relations with Egypt (Kühne 1973:77-78 n.387). This may have been difficult since Assyria would have been a vassal of Mittani at that time.
Yehonatan Hershkovitz
Yehonatan Hershkovitz, 'Aššur-nādin-aḫḫē I', RIA 1: Inscriptions from the Origins of Assyria to Arik-dīn-ili, The RIA Project, 2024 [http://oracc.org/OldAssyrianPeriod/Mittanianhegemony/Ashur-nadin-ahheI/]