This mysterious and influential man first appeared to warn Mulder about Ellen´s Air Force base in the second in the second episode of the first season.
 Deep Throat has provided Mulder a lot of classified infomation, and in doing so he placed his own life in danger. To entice Mulder and Scully into cases they otherwise might had overlooked, to draw them along lines of inquiry that might be disregarded, sometimes even to hinder them from paying to much attention at areas he wanted them out of, Deep Throat rarely answered questions directly, but when he did, it was always on his own terms. He admitted that he had been watching Mulder for a long time from his " lofty position" , and obviously, he knew just as much about Mulder´s work as Mulder himself. He was always an important source to information, whether it was to help Mulder uncover the truth, or to hinder him through misdirection. He was a manipulative, avuncular, and enigmatic man, and before sacrificing himself for his protege in "The Erlenmeyer Flask" , the final episode of the first season, he created a presence in The X-Files.