Cyanea marksii, or Marks' cyanea, is a tree in the bellflower family. It is critically endangered or extinct. The last certain sighting of the species was in 1970.
It is native to North America and was found on Hawaii.
It was named by Joseph Rock in Occas. Pap. Bernice Pauahi Bishop Mus. 22: 52 in 1957.