Eleven
It's strange how some numbers become linked in your head with specific things. The first one for me was three, the magic number. This is the second Eleven. A brilliant character — amazingly acted by Millie Bobby Brown. I don't count Seven because it really should've been seven-of-nine.
I have thoroughly enjoyed watching Stranger Things. Although I was never a DND person. When I was the age of the kids in the TV Series, I was playing computer games, or out causing trouble with my friends. But I did grow up in the 80s in the UK. Some tropes don't match exactly with what was going on in the US. Enough matched though to give me the warm nostalgic feelings while watching it.
One of the things that I loved was how the Kate Bush song played an important role. Then the lyrics themselves took on extra significance in the last season. Keep running up that hill.