Wikipedia has this nice photo of a historical re-enactor dressed as an 1800’s patent medicine broker.

Clark Stanley, likely the most (in)famous snake oil peddler,

After the passage of the pure food and drug act in 1906 championed by Teddy Roosevelt, it was examined and found to have no medicinal value. He was fined and it was removed from the market. Stanley’s product didn’t even contain any snake! It was mineral oil and some other extracts.