due to the fact that the actor had been shaving his head. When Pileggi attended the audition for Walter Skinner, he had been in a grumpy mood and had allowed his small amount of hair to grow back. Pileggi's attitude fit well with the character of Skinner, causing Carter to assume that the actor was only pretending to be grumpy. After successfully auditioning for the role, Pileggi thought he had been lucky that he had not been cast in one of the earlier roles, as he believed he would have appeared in only a single episode and would have missed the opportunity to play the recurring role of Walter Skinner. Glen Morgan and James Wong's early influence on The X-Files mythology led to their introduction of popular secondary characters who would continue for years in episodes written by others, such as the Scully family—Dana's father William (Don S. Davis), mother Margaret (Sheila Larken) and sister Melissa (Melinda McGraw)—as well as conspiracy-buff trio The Lone Gunmen. Writing Initially, there was no certainty as to how long the series would go on, and as a result there was no long-term plan in the beginning to guide its writers. Although the initial impetus for the show was based on alien abduction lore, the crew believed that the series would not be able to maintain its momentum for long if it did not branch out into different plot ideas. The show's first season thus featured numerous standalone stories involving monsters, and also diverse alien or governmental cover-ups, often with no apparent connection to each other—such as the Arctic space worms in "Ice", and the conspiracy of genetically engineered twins in "Eve". Carter himself wrote "Space", an intended bottle episode about the manifestation of an alien "ghost" in the NASA space shuttle program, which was subject to cost overruns and became the most expensive of the first season. By the end of the first season, Carter and his staff had come up with many of the general concepts of the mythology that would last throughout all nine seasons. The first season introduced the series' primary antagonist, Cigarette Smoking Man, and gave early insight into the disappearance of Mulder's sister Samantha, whose abduction provided one of the main plot threads of the series as a whole. The emergent mythology was further solidified in the Carter-penned, Edgar Award-nominated season finale "The Erlenmeyer Flask". The episode was written