Trog (1970)

“From a million years back...Horror explodes into today!”

Anthropologist Dr Brockton unearths a primitive troglodyte — an Ice Age 'missing link': half-caveman, half-ape — in a local cave. Through experimentation, she manages to communicate with and domesticate him before he's released by an irate land developer and goes on a rampage, terrorising the local citizenry.