Homo neanderthalensis: Neanderthals and humans coexisted in Europe and Asia until around 40,000 years ago. While their exact cause of extinction remains debated, competition with modern humans and climate change are thought to be contributing factors.

Imagined image: Left is a neanderthal, right a human. Just as human looks vary widely, Neanderthals did too. This is perhaps one way neanderthals might have looked. The likely looked a bit more human than this too, but this gives you a good idea of the differences.