Marian Walentynowicz (born 20 August 1896 in Saint Petersburg, Russian Empire, died 26 August 1967 in Warsaw, Poland) was a Polish graphic artist, architect, teacher, writer and comics artist in Poland. He is probably best known for his collaboration as illustrator with Kornel Makuszyński in their creation of Koziołek Matołek, a popular classic children's series about a billy goat.