I like this topic, because I'm a sucker for prison fims, especially "b-movie" prison films, which make no apologies for parading cheap sentiment.
My favorites are:
1. "Brute Force," from the late '40's, with Burt Lancaster, and Hume Cronyn exceptionally effective as a viciously brutal guard captain. Great film!
2. "Women's Prison," with Ida Lupino and Howard Duff. Every prison cliche from the '50's, presented without apology, and with conviction. Lupino highly convincing as a hateful, closet-lesbian guard captain victimizing a weepy, semi-innocent blond prisoner (Jan Sterling)unjustly sent away. Incredibly entertaining!
3. "Riot in Cell Block 11," with Neville Brand and Emile Meyer. A "message" film from the '50's that never lets its message (prison reform is needed) get in the way of good old-fashioned rioting and thuggery.