The earliest one I can remember is this: I was probably like 6 years old (irl and in the dream) and I was at my grandmother's home, as usual. It started with me eating with my entire family at the big table in the living room. There was a lot of hanging out with them but it's really not that important and I don't remember most of what I did anyway.
I went outside for a bit and I noticed it was getting really bright, there was an unnatural, muted yellow color in the sky. This really unsettled me, so I ran back home panicking and told my mom to look outside with me. She thought it was weird as well, despite this she continued being calm and said that I shouldn't worry so much, she went inside and left me alone. I was still scared.
Then a bunch of stuff happened that I can't recall, but basically it was announced on TV that a huge meteorite would be crashing on Earth and that my country would be severely affected and that they didn't have the resources necessary to save us. I started crying and thinking "I knew it" over and over again, everyone was either crying, frantically moving around or quietly accepting their fate. My mom and my sister were doing the latter, and they wrapped their arms around me. They whispered things like "it's ok", "it will be over soon" and I would respond with something like "I don't want to die". As the meteorite was getting closer and closer, and everything was getting yellower, the last words we shared were "I love you".
Looking back, it wasn't that bad a dream, but it was extremely realistic (was surprised it wasn't real when I woke up) and I used to have a big fear of the world ending, so naturally I thought this dream was horrifying.