Jules Basile Guesde (November 11, 1845 – July 28, 1922) was a French socialist journalist and politician.
Guesde was the inspiration for a famous quotation by Karl Marx. Shortly before Marx died in 1883, he wrote a letter to Guesde and Paul Lafargue, both of whom already claimed to represent "Marxist" principles. Marx accused them of "revolutionary phrase-mongering" and of denying the value of reformist struggles. This exchange is the source of Marx's remark, reported by Friedrich Engels: "ce qu'il y a de certain c'est que moi, je ne suis pas Marxiste” (“what is certain is that [if they are Marxists], [then] I myself am not a Marxist”).