Mikhail Zalessky (Russian: Михаил Дмитриевич Залесский, Mikhail Dmitrievich Zalesskiy; 15 September 1877 – 22 December 1946) was a Russian paleontologist and paleobotanist. His main focus was an investigation of plant remains in coals and oil shales.In 1911, Zalessky described a new type of petrified wood from the Donets Basin in Ukraine. He called the wood Callixylon, though he did not find any structures other than the trunk.