Terminator 2: Judgment Day (1991)

T2 is the rare sequel built on a genuine idea rather than a bigger budget — though it had that too, as the most expensive film ever made at the time. Cameron's inversion is elegant: the nightmare of 1984 is now the guardian, the new nightmare is faceless and fluid, and the film's real question is whether anyone — machine or mother — can unlearn what they were built for. 'If a machine can learn the value of human life, maybe we can too' is as close as blockbusters get to a thesis statement.

The T-1000 changed cinema. ILM's morphing liquid-metal effects — barely five minutes of screen time, a year of rendering — were the moment digital effects stopped being a gimmick and became the future; every filmmaker alive in 1991 remembers the checkerboard-floor scene. But Cameron backs the pixels with Stan Winston's practical work and real, colossal stunts: the canal chase, the helicopter under the overpass, a tanker of liquid nitrogen. The film's spectacle still lands because most of it actually happened.

Linda Hamilton's Sarah is the dark heart: institutionalized, ripped, half-feral, so consumed by the future that she nearly becomes a terminator herself — her aborted assassination of Miles Dyson is the film's moral hinge. Around her, Arnold gives his career performance as a killing machine learning thumbs-up hesitantly, like a second language. The nuclear-nightmare playground sequence remains the most harrowing depiction of atomic war in mainstream film. Hasta la vista, baby — but it's the thumb sinking into the steel that stays with you.