It all depends on whether you’re a “profit participant” in the show, which gives you a piece of the syndication revenue. On NCIS, for example, Mark Harmon is clearly in that category, but I’d be surprised if the rest of the cast has a cut of syndication profits. William Peterson of the original CSI left after nine seasons but still got paid as a producer, which gave him a share of the syndication profits as well. He’ll make far more off syndication deals for CSI than he ever earned as an actor (and he pulled down over $500,000 a episode at the end of his run).
I’ve read countless stories about supporting actors getting huge paychecks during the last couple of years of a series. In virtually every case, they’re getting their money up front, and will earn little/nothing from syndication and marketing. That’s one reason that virtually every writer on a TV show is also billed as a producer. It not only bumps up their weekly check, it also gets them into the syndication money.
Residuals, thanks to a guy named Reagan.
Nobody but NOBODY has parlayed a TV career into crazy money like William Shatner. Last I saw his net worth was $650 million, including at least $600 million from his Priceline.com stock.