Statler and Waldorf are good but too obvious. One series of videos summons the proper combination of cuteness and batshit insanity that this site embodies, so I nominate Otto the cat.
The best thing is that I saw this on Yahoo!'s front page yesterday, and I laughed to myself thinking "damn, yahoo's really on the pulse of the internet. I only saw this video like 2 years ago." So now I know chet gets his (old) videos from yahoo.
This is how cats will live in space, floating serenely around in their flextubeform suit, only to shoot out a paw occasionally to maneuver and touch your face while you sleep.