Maladaptive daydreaming is a thought pattern in which a person spends a lot of time immersed in fantasies or daydreams. I think I have that too; it used to be worse, but now I'm better. But I understand you, nothing "serious" like dreaming about these people, but I have great admiration and even a certain obsession with these people who have already passed away. To what extent does this harm your life? If you want to send me a private message and we can talk about which people we're talking about, feel free.
I think I have an idea of which people you're talking about.