What's the greatest story ever told about robot consciousness?

We may or may not find an extraterrestrial civilization in your lifetime — but that doesn't mean we won't encounter a different sort of consciousness. Robots could soon be the strangers in our midst, and science fiction has prepared us. What's the best story for understanding how robots might think?

Please share your favorite story about robot consciousness below — and explain why it gives insights into the nature of artificial sentience. Also, please include a picture or video if possible!

Top image: Kim Hyeong Seung, via Concept Robots