Mulder dies watching his porn collection. Mulder and Scully are embraced by vampires. Scully becomes a Ventru, Mulder gets stuck being a Nosferatu. Mulder dies from second hand smoke from old Cigy and Scully decides to get married and settle down. They find the aliens, and then Elvis kills them with a bag of doughnuts.
Random comet destroys the earth.
Due to an error caused by miscalculations in the conversion of metric to english units and someone forgetting to carry the one, the life span of the sun is overestimated and goes nova in 1999. They investigate a string of murders at Camp Crystal Lake, where they meet their comical yet untimely end. They both run off to join the circus. They slip in a puddle of cat puke and break their necks. The x-files is closed permanently so that people can watch baseball or football or whatever.