Seaman was by far one of the creepiest, yet most fun games I've ever played. It came out for the Dreamcast and was one of the only games with a microphone at the time. This fish with a man face would at first just swim around with its brothers and sisters in a tank, eventually to suck the life out of them with a tube on top of its head. You were then left with the last fish standing (or swimming). You awake the next day to find out he now asks questions and wants to learn about your life. A fish with a man-face asking you how your day went. Yup. Awesome. I eventually trained mine enough to become a moth-like creature and then die.
Also, here's an extra drawing I did a few months ago. The man-face hyenas.