usually people mean entire franchises and fandoms when they ask this, so uh... star trek!

i wouldn't be who i am without it, it's a bit of everything for me. a beautiful vision of a future where humans learn to cooperate with one another and solve their problems with compassion and reason. stories about overcoming adversity, the balance of logic and emotion, the importance of diversity and respect for other cultures, how even in this utopia evil arises and how it is defeated, and many other things. and for all the episodes that are philosophical thought experiments or real-world allegories, it still manages to be great as an action show when it needs to be. even on a shallow aesthetic level star trek has always been very good, full of high-tech coolness.