House Velaryon didn’t disappear in Game of Thrones ; it simply became a much smaller, less visible house by that era. The real turning point was the Dance of the Dragons, which badly damaged their fleet, power, and influence.

What changed

  • House Velaryon was once one of the most powerful naval houses in Westeros.
  • During the Targaryen civil war, they lost ships, people, and political leverage.
  • After that, they remained tied to Driftmark and continued as a noble house, but they were no longer a major force in the wider realm.
  • In the Game of Thrones period, they are mostly offscreen and only lightly mentioned compared with the Targaryens, Starks, or Lannisters.

Why they seem absent

By the time of Game of Thrones , House Velaryon is basically a shadow of its former self, so the show has little reason to spotlight them. Their name still exists in the lore, but their influence is much diminished after generations of decline.

In one line

House Velaryon survived, but after the Dance of the Dragons they lost the power that once made them important.

TL;DR: They weren’t wiped out; they were reduced from a major Valyrian power to a minor house by the time of Game of Thrones.