I'm just wondering something about Babylon 5. I know that in the middle of the first season we end up seeing a Shadow ship at some point for the first time, but only briefly. But when was the very first verbal reference to the Shadows made? Thanks.
The first verbal reference to the Shadows occurs in the Season 1 episode "Signs and Portents", when Londo and Lord Kiro (a Centauri nobleman) debate Lady Lahira's vision about Babylon 5's destruction:
LONDO: Then you don't believe her vision?
LORD KIRO: She's been wrong before. On my first birthday, she said that I would someday be killed by "shadows".
LORD KIRO: Doesn't exactly make sense, does it?
At the end of the episode,
Lord Kiro is killed by the Shadows. This is, in fact, the appearance of the Shadow ship that you refer to. It materializes briefly and destroys the raider ship that Lord Kiro is on.