1st appearance and origin of Spider-Man 2099

5-page preview in Amazing Spider-Man #365 and an advertisement in Web of Spider-Man #90

⚠️ Debatable Firsts: many sources cite Amazing Spider-Man #365 as the first appearance of Spider-Man 2099 despite text on the cover of the issue that refers to it as a five-page preview promoting Spider-Man 2099 #1