Dr. Rainbrain

From Muppet Wiki

Dr. Rainbrain appeared on Sesame Street in a sketch with The Count. They had spent days and days building the Transylvanian Rocket Ship, and have just completed their work. When they count down, the rocket ship doesn't blast off, which makes Count count down again in "Transylvanish," causing Dr. Rainbrain to go insane. At the end, Count says "One crazy scientist!"