It's safe to say the early aughts WB series "Buffy the Vampire Slayer" was a smash hit — among other accolades, it produced a five-season spin-off, "Angel," and launched several storied careers, including that of its controversial creator, Joss Whedon. A few of the "Buffy" characters returned in "Angel" after departing from "Buffy," including the British Watcher Wesley and Sunnydale High's resident mean girl Cordelia. Even Spike, who was killed off in the "Buffy" series finale, returned for the final season of the spin-off. However, not all of the cast members were so keen on reprising their roles after the original series ended.

Emma Caulfield stars in "Buffy" as the minor character Anya, a wish-granting vengeance demon who is turned back into a human and forced to attend high school where she falls in love with Buffy's hapless human sidekick, Xander. She became a recurring character in season 3 before falling into...