One of my recurring dreams is where my old coach of 12 years (was like a member of my family) would randomly come find me. I get all excited and be like "OMG I have to call mom! They'll be so excited to see you!". Every time he says "No, I just came back for you, to let you know I'm alright. But no-one else can see me." The crazy thing about this one is, I had it many many times for years before I finally found out he actually died in real life.
And I have another recurring one about a friend who commited suicide in HS. That one doesn't bother me really though cause in it, we both recognize he's actually dead. So it's just like I'm hanging out with a dead dude.