10 Deadliest Accidents In Star Trek
4. Borg Survival Course
Here's a sentence you won't hear often — let's give the Borg the benefit of the doubt! We don't know what caused the crash of the Borg Sphere on Planet 1865-Alpha in the Delta Quadrant, shown at the start of Survival Instinct. The Collective was hardly averse to sacrificing the odd vessel when it suited, but by all accounts, this was not a deliberate act. It was definitely deadly.
In Unimatrix Zero, Part II, the Borg Queen herself noted that "sphere 878" had a complement of "eleven thousand drones". Taking that figure as standard, the morbid calculation is a simple subtraction. The only survivors of the crash in Survival Instinct were Two of Nine (Lansor), Three of Nine (Marika Wilkarah), Four of Nine (P'Chan), Seven of Nine, and a mortally wounded drone, designation unknown. Eleven thousand minus four.
Of those four, three probably wished they were dead. No accident this time, but the desperate, last-ditch effort of a frightened Seven of Nine down on the planet in 2368. Through new interlink nodes created by Seven's nanoprobes, Wilkarah, Lansor, and P'Chan were trapped in a "neural triad" — a collective within the Collective. Breaking that bond once they were out left them with only a few months to live. Eleven thousand minus one.