9. "Yesterday's Enterprise" - Star Trek: The Next Generation
The first two seasons of Star Trek: The Next Generation were wildly inconsistent, and one of its most baffling early episodes was season one's "Skin of Evil," where Lt. Tasha Yar (Denise Crosby) was unceremoniously killed off by the risible tar monster Armus (Mart McChesney).
Despite Tasha Yar being a prominent character, her death came totally out of nowhere as a result of Crosby requesting a release from her contract for not receiving satisfactory screen time.
But rather than getting a memorably dramatic demise, she ended up killed instantly by a psychokinetic blast with all the pomp of a redshirt day-player.
Season three's "Yesterday's Enterprise" attempted to make this up to both fans and Crosby by bringing the actress back to play an alternate timeline version of Tasha.
Amusingly, upon learning of her lousy demise in the original timeline, alt-Tasha even calls the death "senseless" to Picard (Patrick Stewart), and insists that if she needs to die, she wants it to count for something.
The episode ends with Tasha embarking on a heroic suicide mission, giving the character a far more fitting end - at least until the season five premiere "Redemption" reveals that she survived the suicide mission, became a Romulan sex slave, gave birth to a daughter (also played by Crosby), and was later executed. Oof.
Even so, it successfully remedied Tasha's underwhelming flunky death in season one.