Not even one generation, the entire runtime is not even 10 years, and you’d have to be in a rather small age bracket to get the full brunt of the “cultural” impact. My parents’ generation watched it, but it wasn’t really all that different from everything else for them.
It’s actually super interesting to see the fall of GoT. It fell into oblivion almost immediately after the last season finished.
It’s really wild. Even in my own life we watched each of the first six seasons over and over while waiting for new ones. By the end of it I felt no need. I barely remember how it ended and have no desire to watch it. Kind of sucks, I think I’m right in that age bracket that it was a big deal for. No lasting impact. Like Avatar
Semi-serious answer. Greeks like Homer and Euripades and Virgil, the bible, Shakespeare. Lots of Western pop culture is a rehash of old stuff.
Answering the question more as you likely intended. Pokemon. Harry Potter. Star Wars. The MCU.
From what I suspect is due to my personal bubble, Star Trek; ST pops up several times per week in my life. And Twilight, I’ve got a group of friends who are queer and will jam a Team Alice or KStew reference in at every opportunity. It seems like the rest of the world has moved on from Twilight love and Twilight hate, but this group is keeping the discourse alive.