One of the most common nightmares, period, is the nightmare in which someone or something is chasing you. It could be a single human being, it could be a monster, it could be someone in a vehicle or it could be a horde of zombies - and all of them are said to represent the same thing. In a nutshell, this dream represents anxiety. Sigmund Freud himself suggested that they are a manifestation of our worries, whether they be menial worries about arriving somewhere on time or whether they be serious concerns about health or mortality - we're anxious about something if we dream about being pursued. Essentially, if you're trying to get away from someone or something in your dreams, there is a concern in your life that you would like to try to avoid. This dream represents one of the clearest metaphors for its true meaning - assuming you believe in that kind of thing anyway.
