The 1950s saw the release of some of the best sci-fi chillers ever. One of the best of the best is Don Siegel’s “Invasion of the Body Snatchers,” unreeling Feb. 18 at BAM Rose Cinemas in Brooklyn. The black-and-white chiller  features Kevin McCarthy as a small-town doctor who discovers that pod people are colonizing the earth, replacing humans with soul-less lookalikes. Dana Wynter plays the doc’s girlfriend and King Donovan and Carolyn Jones  his best friends. Sam Peckinpah has a cameo as a meter-reader. The film was remade twice, but Siegel’s original is still the one to see. The original ending is a gem —  pity the studio forced Siegel to add a lame framing-device. Village Voice critic  J. Hoberman will introduce the BAM screening. Details: bam.org