Karl Daniel Adolph Douai (1819 – 1888), known to his peers as "Adolph", was a German Texan teacher as well as a socialist and abolitionist newspaper editor. Douai was driven from Texas in 1856 due to his published opposition of slavery, living out the rest of his life as a school operator in the New England city of Boston. Douai is remembered as one of the leading American Marxists of the 19th century as well as a pioneer of the Kindergarten movement in America.