My most recent nightmare was this morning just before I woke up. It involved a disaster scenario where the Earth was being gradually taken over by aliens called Experians (isn't Experian a company? Name sounds familiar anyway). They destroyed people by topological operations, mapping parts of a person's body to other parts, and thus turning you inside out in implausible and revolting ways. The story of the dream revolved around a middle-aged American couple lying in bed discussing the Experian threat. The woman was gradually succumbing to the alien topological thing: it could be induced telepathically, but operated fairly slowly that way - the early symptoms were similar to a bad cold. By contrast, if one came into physical contact with an Experian, the destruction would be very rapid. Suddenly the lights went out, and they realised the power must have been lost, which would also mean the electric fence round their property was no longer operational and excluding Experians. The man got up to go and see what was happening outside, and the woman hid under the bedclothes in fear. At this point I was transported into her position (I had been a disembodied observer until then) and heard footsteps approaching the bed. The cover was pulled back; I saw a human-looking hand, then peeked round to see the head...which was a horrible mutated inverted mass of brains and skull and eyeballs! I tried to scream but my voice stuck in my throat. Then I woke up.

Actually I have quite a lot of nightmares about alien invasions.

My first nightmare, when I was a toddler, involved my mother being torn to pieces by wild animals in front of me - then the animals surrounded me and moved in for the kill.