It is interesting to keep an eye out for guest (and sometimes semi-regular) high-quality actors in American Sci-Fi series.
Some of the more recent series, such as Earth: Final Conflict and the new versions of V and Battlestar Galactica, have previously unknown (at least to most of us) performers more-or-less throughout, although the latter did have the excellent Michelle Forbes guesting as Captain Caine of the Pegasus for a couple of episodes. I first encountered Michelle as the Bajoran ensign Ro Laren in Star Trek: The Next Generation some years earlier.
Other series, such as Andromeda and Stargate SG-1 have featured easily-recognisable actors like Peter Wingfield, Sam J. Jones, Tony Todd, John Savage, Carmen Argenziano, Hiro Kanagawa and Kevin Durand, among others. If you want to see what I mean, pick a name from that list and take a look in Google Images and you'll immediately say to yourself "Oh, him!' and probably follow that with 'I wondered what his name was..." Betcha!
I, of course, have (predictably!) been storing these names mentally for years, and a large number of others too, starting decades ago with names that most people alive today wouldn't recognise, such as Jeff Corey (not a brilliant actor, by the way, but always enjoyable to watch, funnily enough) and Michael Cavanaugh.
The series are good showcases for acting talents, as the characters are often more interesting than parts in other genres. For example, Sam J. Jones – hardly one of the greats in terms of acting – had an excellent outing in SG-1 as a bounty hunter in one episode. It really suited his style! It was certainly a long way from the movie Flash Gordon he played all those years ago, opposite Brian Blessed and Timothy Dalton...
Sometimes bringing relatively unknown names into prominence in a big production can work – and sometimes it just doesn't. The new V was cancelled after two seasons owing to poor viewing ratings (all-important in American TV!), and I am reasonably certain that this was largely down to the relatively low acting standard and lack of believability of the main characters – apart from the always-excellent Morena Baccarin as Anna, who was the only name I recognised from the entire cast.
Mind you, Christopher Sher who plays Marcus looks to have potential, but the only other really good performer had his character killed off in the very first episode (Alan Tudyk, who was great in both Firefly and Dollhouse).
Conversely, the Galactica cast turned out to be generally up to the challenges, so that despite the dodgy (almost free-wheeling) writing style of the series, it did go all the way to the story's conclusion. Some of the regular cast made names for themselves in that series and have since appeared elsewhere – perhaps most unexpectedly 'Baltar' becoming Merlin in one production(!)
It's a funny old business, though; and the tendency of series to be cancelled after just one or two series (anything with Eric Close in it seems to last just one season, such as Dark Skies and Now and Again) means that one should never get too deeply into an American series because of the risk of being left hanging.
It can happen here too, though it is relatively uncommon. For example, a number of years ago, two of the three stories of The Tripods were made into a series each, but the third and final story was never made. That was frustrating, as it had become far more interesting during the second season than the first.
I bought the book, though, so I know what happens!