Zig-Zagged in the season 5 finale of M*A*S*H: Margret gets married to Lt. Col. Penobscott and flies away on a chopper, ostensibly for her honeymoon but looking for all the world like she's leaving the series. The last shot of the episode is Frank waving goodbye as she disappears over the mountains. Come season 6, Margret comes back from her leave as scheduled and it's Frank who has left the series.
In season 2 of Boardwalk Empire Van Alden is charged with murder and has to flee Atlantic City which eliminates his role as the antagonist to the gangster Nucky Thompson. In the premiere of season 3 Van Alden is living in Chicago under an assumed name when a very Contrived Coincidence places him right in the middle of the conflict between gangsters Dean O'Banion and Al Capone.
I removed these two because I don't think they're examples of this trope. If a character spends the whole finale planning to leave, then decides at the last minute not to, that's this trope, but if they actually do leave and then return in a later season, that's a different trope.
I removed these two because I don't think they're examples of this trope. If a character spends the whole finale planning to leave, then decides at the last minute not to, that's this trope, but if they actually do leave and then return in a later season, that's a different trope.