Lost: Shannen Doherty
And Found: Rose McGowan for Charmed, Tiffani Amber-Thiesen for 90210
Bummer. Poor Shannen Doherty abandoned Charmed after its third season, and the show continued a successful run in five more seasons with Rose McGowan in her place.
Not to mention how Shannen left 90210 after its fourth season, and ended up with Tiffani Amber-Thiessen as "bad girl" Valerie Malone in her place for the majority of remaining seasons.
