TVGuide.com reported some casting news from Eric Kripke, creator and executive producer of Supernatural. At the Supernatural panel at San Diego Comic-Con, which was held July 24-27, Kripke revealed that in season 4, Mitch Pileggi of X-Files fame will portray the father of Mary Winchester, which makes him the grandfather of Sam (Jared Padalecki) and Dean (Jensen Ackles). In earlier hints about the upcoming season, Kripke had already talked about showing the Winchester parents as teenagers.

Supernatural, like the X-Files was for many years, is filmed in Vancouver, and a number of X-Files alum have worked on Supernatural, including Kim Manners, David Nutter and John Shiban. Steven Williams, who played Agent Mulder's informant "Mr. X," appeared in the season 3 episode "Time Is On My Side" (and according to Eric Kripke, will be returning in season 4). William B. Davis, who played the Cigarette Smoking Man, had a role in the season 1 episode "Scarecrow" (directed by Kim Manners).

As Assistant Director Walter Skinner on The X-Files, Mitch Pileggi portrayed Agent Mulder and Scully's ally within the system with authority and a strong presence, often risking his job and sometimes his life to help his agents. He also had a prominent role on Eric Kripke's prior TV series, the short-lived Tarzan. He most recently can be seen as Colonel Steven Caldwell on Stargate: Atlantis, and it's his voice you hear as Jim Gordon on the animated series The Batman.

At the panel, Eric Kripke also teased the first five minutes of season 4 for eager fans, and stars Jensen Ackles and Jared Padalecki were also on hand.

Source:
TVGuide.com