Krycek tries and fails to kill the now wheelchair-bound Cigarette Smoking Man by pushing him down a flight of stairs.[7] Later, when Mulder was abducted by aliens and returned in a deathlike state, Krycek attempts to again blackmail Skinner, with the means to save Mulder's life. Skinner refuses, and Krycek has a violent confrontation with John Doggett before escaping.[8] In the season eight finale, "Existence", Krycek is shot between the eyes and killed by Skinner, during an unsuccessful attempt to kill Mulder.[9] Krycek's ghost briefly showed up to help Mulder escape a military base in the series finale.[10]
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But: The X-Files Season 10 (comic book) in the first part of a five-part story Krycek appears to have returned from the dead in Saudi Arabia, where a store of black oil has been tapped. He helps Mulder escape an attempt on his life.
The comic is overseen by Carter so it may be canon