George Marx (June 22, 1838 – January 3, 1895) was a German-born American arachnologist, scientific illustrator and physician.

At age fourteen he entered a gymnasium (high school) in Darmstadt with the expectation that he would follow his father into the ministry.

While at school Marx became interested in botany and displayed such an aptitude as an artist that he was employed to illustrate a book on the local flora.

At the outbreak of the Civil War he enlisted in the Union Army and served as a private until the First Battle of Bull Run in July 1861.

He was recognized as an authority on spiders and collaborated with noted arachnologists in America and Europe including Tamerlan Thorell, Eugène Simon, James Henry Emerton and George Williams Peckham.

Marx completed and edited Die Spinnen Amerikas (The American Spiders) which had been left unfinished by the death of the original author, Eugen von Keyserling.