In serial dramas and comedies it occasionally happens that the actor playing a regular character needs to be replaced. The character isn’t written out of the show; they just start being played by a different performer. Sometimes this is done without any in-universe comment—perhaps the producers hope the audience won’t notice or won’t care—though sometimes there’s some story-internal explanation for the character’s change in appearance.
I’m wondering if any live-action TV show has permanently replaced more than one regular character’s actor simultaneously. Can anyone name any examples? If you watched such a show, did you find the sudden replacements jarring?