When I was a little kid, I watched
Alien from the Deep (original Italian title: "Aliens del Abismo", French title: "Alien : La Créature des Abysses") and the French title was even more misleading than the other ones, meaning literally Alien : The creature from the abysses".
So I honestly thought this terrible, terrible movie was somehow PART OF THE ALIEN SERIES. I was convinced of it for YEARS. Until I was 16 or something I was still trying to reconcile it with the Alien lore and timeline.
Full movie: