Alchemist

Alchemists were early chemists who worked in the medieval and early modern periods (and a few even survived into the Age of Enlightenment; Newton in particular is sometimes mocked for believing in alchemy). Like modern chemists, they thought matter followed specific rules and would reliably change at different heats, proportions, etc. Unlike modern chemists their rules were rather... derpy. They thought, for instance, that examining an object physically would reveal its internal properties, and spent lots of time in chemically useless pursuits like trying to find phlogiston, an imaginary chemical that was responsible for combustion, or, most famously, trying to turn lead into gold. A similarly-derpy tradition in Asia revolved around making various potions, most notably their quest for the legendary elixir of immortality which mostly yielded a plethora of potions of mortality, since they thought the primary ingredient was the highly-toxic element of mercury. Nonetheless they did stumble upon a few useful ideas, like gunpowder.

In the modern age, they're generally thought of as bumbling primitives at best and devious charlatans at worst, but they played an important role in keeping science alive in an age where research wasn't much of a thing and providing by accident some useful information for chemists.