M. giganteus

M. giganteus may refer to:
 * Machairodus giganteus, a large saber-toothed cat species found in Europe, Asia, Africa and North America during the Miocene and Pleistocene
 * Macronectes giganteus, the southern giant petrel, a large seabird species of the southern oceans
 * Macropus giganteus, the eastern grey kangaroo, a marsupial species found in Australia
 * Mastigoproctus giganteus, the giant vinegarroon, a whip scorpion species found in the southern United States
 * Mastodonsaurus giganteus, an extinct amphibian species from the Triassic
 * Megadytes giganteus, a large diving beetle species found in the Caribbean and in South America
 * Megaloceros giganteus, the Irish elk or giant deer, an extinct mammal species found across Eurasia during the Late Pleistocene
 * Menodus giganteus, an extinct brontothere species
 * Meripilus giganteus, a mushroom species
 * Miscanthus giganteus, a large perennial grass hybrid of Miscanthus sinensis and Miscanthus sacchariflorus native to Japan
 * Mosasaurus giganteus, an extinct carnivorous aquatic lizard species that lived during the Cretaceous