He is best known for almost becoming the pharaoh of Egypt, and because his death caused a diplomatic incident between the Hittite and Egyptian empires, resulting in warfare.
The Egyptian Queen Dakhamunzu, who could have been Meritaten or Nefertiti, but is most often identified as Ankhesenamun, asked Suppiluliuma I to send over a son during the late Eighteenth Dynasty of Egypt because she had recently been widowed by the death of Nibhururia[1] (possibly Akhenaten, but more likely Tutankhamun), and had borne no heir.
This could have led to efforts to make Egypt part of the Hittite Empire.
Zannanza never made it past the Egyptian border, though exactly what became of him and how he died is unknown.
Angry letters were passed between the two nations, but the matter ended inconclusively.