I don't recall any B5 regulars ever guesting on SG1, but, a Lucian Alliance guy that appears in Episode 16 of Season 9 (And for 4 more episodes) is played by Eric Steinberg, who was in B5 S3 episode Exogenesis
Jacob Carter showed up as a Centauri once.
That's right he played Urza in Knives
, I noticed that last time I watched through B5, and then forgot all about it
One Day I hope to be the Man my Cat thinks I am
Where are we going? And why are we in this Handbasket?