Michael Rosenbaum, aka Lex Luthor, is leaving Smallville, which isn’t a surprise, since he said last year that he was probably going to leave. It’s a good example of a departure that is done in a way that avoids any loss of good will for the actor: first he hints at it, allowing the writers to lay the groundwork for his departure while he’s still on the show, then he officially announces he’s leaving when the writers have already figured out how to replace him, and he’ll come back as a guest star. Topher Grace followed a similar pattern on That ’70s Show — his last season on the show was essentially one long set-up for the (impossible, as it turned out) task of doing the show without him. In this way, the actor gets to leave, but he doesn’t get people angry at him for leaving, either the network/studio executives or the fans.
Of course Smallville has pretty much run its course, and its first Lex-less season will probably be its last. It brings up the question — I seem to have been building most of my recent posts around the theme of when/if actors should leave a show — of whether it’s better for an actor to stick with a show until the bitter end, or leave just before it ends. It may sometimes help the show in a strange way: a show in its seventh or eighth year is probably running out of ideas, and losing an important character can actually force the writers to try something new; it may not be as good as the best episodes of the show’s prime, but at least it’s often better than an aging show that’s trying to do what it did before. And then on the other hand it can make the whole show seem pointless and make it all the more clear that the show should have ended already: this is how you wind up with, say, the ninth season of All in the Family where Mike and Gloria didn’t appear (except in one two-parter as guests; when actors leave on friendly terms, they usually come back for a guest shot). As for whether it helps or hurts the actor to leave before the show is over, I don’t know if that’s clear.
Usually the actor has something else lined up when he/she leaves, and usually that something is not a hit, just because the law of averages states that most things aren’t hits. You could make the case that very often, when actors leave a show, they think that they’ll finally be able to take advantage of all the opportunities they had to pass up when they were under contract to the show — only to discover that, without being under contract to a show, they’re given fewer opportunities. The classic case is Kate Jackson, whose Charlie’s Angels contract forced her to turn down some great parts, including the role that went to Meryl Streep in Kramer vs. Kramer; but when she left the declining Charlie’s Angels, it didn’t lead to parts of that caliber, because she no longer had the same name recognition she had when she was on Angels. Kind of a Catch-22: you can only get the good parts if you leave the show, but if you leave the show, you won’t get the good parts.
That doesn’t have much to do with Michael Rosenbaum, though. But here’s something that does: not only is Rosenbaum Lex Luthor, he was also the voice of The Flash on all the seasons of Cartoon Network’s great “Justice League” series. (There was one episode where they had the Flash switch bodies with Lex Luthor, just so Rosenbaum could voice Luthor for one episode.)