A mad scientist is generally called "mad"/ "insane", because of unsettling characteristics, and the dangerous/questionable experiments they run and work on. For example, the creator of frankenstein, from 1818, was said to be a mad scientist, this isnt like the green monster, its the person who sticked different things to different people and tried to run electricity through it to act as a heart, also just to see if he could create a human like creature. THATS a maad scientist, but the stereotype mad scientist according to wikipedia, is white male, aging, crooked teeth, messy hair, lab coat, green glowing liquid filled test tube, goggles, gloves, and striking a dramatic pose while cackling evilly
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