9. The Mother Was Dead All Along - How I Met Your Mother
While it may not rank as one of the most satisfying of unexpected TV twists to have ever left a devoted set of fans in a spell of stunned silence, the reveal of How I Met Your Mother's titular focus actually being dead by the time the mammoth story was being told to her children still ranks as one of the most surprising storylines to have ever graced the small screen.
Entirely reframing the tale unfolding for nine seasons from the second the twist was unleashed onto HIMYM maniacs, the show's series finale threw a jaw-dropping curveball in the form of Tracy McConnell's tragic demise due to illness that left many with a rather bitter taste in their mouths.
Sure, it added a rather heartbreaking layer to the whole series, with Ted Mosby's recounting of this coming together of two lovebirds actually acting as a way of bringing his kids around to the idea of him asking Aunt Robin out in the present day. But the soul-crushing reveal of Tracy's all too short time in the show's spotlight was the sort of surprising bait-and-switch that likely did more damage to HIMYM's reputation than good.