The Twilight Zone. Maybe dated and strange to modern eyes, but the suspense is still there, even on the third or fourth or umpteenth viewing. It didn't hurt to be black & white, either. And there was always a message of some kind. Sometimes you had to dig for it, other times it was obvious. And of course there was Alfred Hitchcock Presents. Chilling stuff. But Hitch left you smiling.
Ten favorites of mine: Citizen Kane (1941) How the West Was Won (1962) King Kong (1933) The Train (1964) Rocky (1976) The Big Parade (1925) Napoleon (1927) Batman (1989) Intolerance (1916) Faces of Children (1925) Hope I've provoked some discussion.