Wikipedia
"Tooms" is the twenty-first episode of the first season of the American science fiction television series The X-Files. It premiered on the Fox network on April 22, 1994. "Tooms" was written by Glen Morgan and James Wong, and directed by David Nutter. The episode featured Mitch Pileggi's first appearance as Assistant Director Walter Skinner, and saw Doug Hutchison and William B. Davis reprise their roles as Eugene Victor Tooms and The Smoking Man, respectively. The episode is a "Monster-of-the-Week" story, a stand-alone plot which is unconnected to the series' wider mythology. "Tooms" earned a Nielsen household rating of 8.6, being watched by 8.1 million households in its initial broadcast; and received positive reviews from critics.
The show centers on FBI special agents Fox Mulder ( David Duchovny) and Dana Scully ( Gillian Anderson) who work on cases linked to the paranormal, called X-Files. When mutant serial killer Eugene Tooms, last seen in " Squeeze", is released from prison, Mulder and Scully try to stop him from resuming his killing spree. Tooms, however, sets out to frame Mulder for assault before the agent can apprehend him.
After seeing men working on an open escalator in a mall around Christmas time, Glen Morgan decided to revisit the character of Eugene Victor Tooms, from the first episode he and co-writer James Wong wrote for the series, "Squeeze". "Tooms" introduced the character of Walter Skinner, although this would be his only appearance in the first season. The character had been conceived as playing against the stereotypical bureaucratic "paper-pusher", being instead someone more "quietly dynamic".