Would “Beserker” by the ancient alien killing machines in older scifi? Arguably a greater threat than the Borg.
Yup. Fred Saberhagen.
https://en.wikipedia.org/wiki/Berserker_(novel_series)
It’s one of the myriad possible explanations as to why the universe seems so empty. Because if anyone does any thing too advanced, they then get noticed. And something comes and exterminates them.
Freegards