10 Times Main Characters Killed Each Other
5. Solid Snake Killed Big Boss - Metal Gear Solid 4: Guns of the Patriots
Metal Gear Solid 4: Guns of the Patriots concludes with a battery of big surprises, perhaps most shockingly that Big Boss - the protagonist of the previous game in the series, which was a prequel - is actually still alive.
He unexpectedly shows up for an expository chinwag with Solid Snake at Arlington National Cemetery in the game's basically feature-length ending cutscene.
Once they're done gassing, Big Boss informs Snake that he himself is not long for this world, as the new strain of the FOXDIE virus coursing through Snake's body was programmed by The Patriots to kill three people - Eva, Ocelot, and Big Boss.
And so, after imploring that Snake make the most of his remaining time and find a reason to keep living, Big Boss finally unambiguously expires at the grave of his own mentor, The Boss.
While you can technically say that the Patriots really killed Big Boss, Snake was still the delivery system, and without his proximity to Big Boss, he wouldn't have shuffled off his mortal coil quite so soon.