D&D 1977, my next door neighbor's grandson, a couple years younger than me, when he visited, I was the kid in the neighborhood that played with him. That year, I was 15, he was 13, he suffered dyslexia and his teacher recommended he play D&D for all the reading required. But I didn't start playing regular weekend games until the summer of 1979.
Star Wars 1976, I saw an article about the coming first movie in some 8th grade weekly reader type publication. Then saw it at the theater the first day it was released in 1977.
The Hobbit/Lord of the Rings (you didn't mention this, but I think belongs on this list). Summer of 1977, between 8th grade and high school. (Notice how key 1977 was for me, at least regarding this list.)
Earth Sea, I found UKL sometime in high school, say 1980 would be my guess, I read the trilogy. I read them, they were okay...
H. Potter, eh, I think I saw one of the movies, on TV, I didn't go to the theater for it, and certainly didn't read the novels, and hardly intrigued.
Marvel/DC, I've always been aware of them, and aside from a few issues of horror comics like Uncle Creepy, Cousin Eerie and Vampirella, I was never into comics, and am really not into the movies, though have seen my share a various movie Supermans and Batmans, a Spider man, and have avoided the rest for the most part, except catching one of them on TV at somebody else's home (I don't watch TV at home).
Dr. Who, probably sometime around 1980 (the 80's anyway), when Tom Baker played Dr. Who, and it was on Channel 11 PBS. I've seen an episode or two of the newer Dr. Who's, I was never a big fan.
Star Trek, despite having been already alive when they were first aired, I was like 2 years old, but my parents didn't watch it. So while I could have experienced the original airings, I didn't notice Star Trek until the re-runs in the 1970's. I also went to 3 or 4 of the Star Trek movies when they were first released.
Also only tangentially related to this list, at least from my perspective, in July/August of 1977, I purchased Lafcadio Hearn's Kwaidan, a collection of Japanese ghost stories translated to English and other works, at the airport bookstore, and read it on the flight to my second trip to Japan, where I even visited the author's home in Kyoto. The first story, Mimi-Nashi, Hoichi (Hoichi the Earless) would inspire me to develop and publish my Kaidan setting of Japanese Horror (PFRPG) 2010-17...