7. Viggo Mortensen - The Lord Of The Rings: The Two Towers
Viggo Mortensen sure endured his share of suffering while shooting the Lord of the Rings trilogy. For starters, he chipped a tooth, got a black eye and broke two of his toes, but worst of all, the guy very nearly drowned.
While shooting the scene in which Aragorn floats down a river, the crew underestimated the strength of the current and Mortensen was swept away, which combined with the hefty weight of his armour nearly made him unable to extricate himself.
Considering Aragorn's pivotal role in the movies and the fact that all three films were shot back-to-back, it's safe to say Mortensen's death would've been an insane headache, even more so than a cast member's death usually is.