Jess Nevins posits a new possible origin for the mad scientist archetype. The following is from Christopher Smart’s 1745 poem “Temple of Dullness”
Next to her, mad Mathesis; her feet all bare,
Ungirt, untrimm’d, with loose neglected hair;
No foreign object can her thoughts disjoint;
In this poem you’ve got: the phrase “mad Mathesis” (i.e., “mad science”); a scientist with “loose neglected hair” (and it’s de rigueur for mad scientists to have unkempt, wild hair); a scientist “arrogant and vain” (although numerous previous poems had assigned anti-religious scientists these qualities) (Smart is attacking anti-religious scientists here, not scientists as a whole–note his invocation of “great Newton”); and a scientist creating “trifling trinkets” and “gewgaw toys” (not a lot of distance from a mad scientist creating those to creating a death ray).
(Image is of Samuel Hahnemann, who wasn’t born until 1755)