In the first Elite game,
Thargoids would pluck your ship out from jump space and fight you in deep space.
If you had the basic fit for your cobra, (which pretty much meant starter weapons) they were hard to kill. The ships resembled flying saucers and had heaps of hit points. The pulse laser of the first game fired like a bolt action rifle.
If you did destroy them, they dropped tonnes of alloys which could get you a decent profit.
All this is information when I played the game 25 years ago.
I believe they made an appearance in Frontier First Encounters, but I never got too deep into that game for them to even get on my radar.