Odd Coupling

In terms of offbeat guest stars on The X-Files, it's hard to beat former game-show staple Charles Nelson Reilly, who appeared on the program last year as an idiosyncratic novelist. But the hit Fox series will top that this season when Richard Belzer appears as the quirkily unflappable Detective Munch from NBC's cop drama Homicide: Life on the Street. The rare inter-network crossover came about when The X-Files' producers decided to set an episode (airing Nov. 16) about the origins of the conspiracy nerds known as the Lone Gunmen on Homicide's home turf, Baltimore. Much to Belzer's delight, Files supervising producer Vince Gilligan decided to ask some friends on the Peacock drama for a favor. ''They didn't realize I'm a huge fan of the show,'' says Belzer, who shot his spot in August. ''I'm into the paranormal — UFOs, 12 Oswalds, three versions of me running around — so I was like a kid in a candy store on the set.'' Now that Files is making a habit of wacky walk-ons, who's next? ''We'd like Wayne Knight from Seinfeld,'' says Gilligan. ''He's actually got a secret life that we don't know about: Special Agent Newman.''