Episodes 8 & 9 of Season 1; Ice and Space.
For Ice we take a trip to Alaska for the X-Files' version of The Thing complete with paranoia and probable alien life. As Kim notes this is the first time we've seen alien life on-screen in the series.
Then of course, we get ghost aliens, some confusing special effects and the apparent reveal that the FBI are essential help in space crisis' in Space.
Kim's Conspiracy Corner attempts to fit ancient aliens and space ghosts into the overall whole.