Who is the dancing baby? I don't really know. I don't know who created him/her. But, it's world-famous. Well, web-famous anyway. Just goes to show you what truly creative people can do, with alot of free time. This is an animated GIF. It doesn't do the real movie justice, especially when set to music (there are several actually). From what I understand, the original movie was created with 3D Max software.
Oddly, my mother found it somewhat disturbing (odd because my mom is one easy-going, well-humored lady) in that it was a baby, moving like an adult. I guess I can see her point, but mostly, I think it's just funny.