The X-Files: 10 Best Mythology Episodes

NOTE: Can the title be changed to Piper Maru/Aporcrypha cheers!

By the time season three of The X-Files rolled around, Mulder and Scully had already accumulated a fair amount of regular foes during their quest to unearth the truth. Krycek, Cigarette Smoking Man and the Alien Bounty Hunters had already left distinct marks on both our agents, but with the two-parter 'Piper Maru' and 'Apocrypha', we were introduced a much more insidious and gooey kind of villain.

The story starts with the unearthing of a long-lost military vessel known as the Piper Maru, which was home to the Black Oil, a sentient goo that is capable of possessing anyone that comes into contact with. We see it move from host-to-host until it finds its way into Krycek - who at the time is under arrest by Mulder.

What follows is a fast-paced story that seamlessly balances numerous plot-lines with aplomb and adds in a new faction to the ongoing struggle between our heroes, the government and the extraterrestrial forces. Further down the line we'd find out more about the mysterious substance and its significance within the show's overall story, and whilst later Black Oil centric episodes weren't shining examples of the show's quality, this two parter is the perfection introduction for such an important facet.