The Quatermass Xperiment

A spaceship returns to earth with only one man of a three man team left on board. After examining the rocket, Quatermass concludes that out in space some mysterious force entered the rocket and the lone survivor, Victor Carroon, has been infested by an alien entity. Before they can contain him, Carroon escapes. Quatermass joins forces with the police to track Carroon down as he gradually transforms into a hideous monster which searches for human victims with which to feed itself. (Park Circus)