George James Allman FRS FRSE (1812 – 24 November 1898) was an Irish ecologist, botanist and zoologist who served as Emeritus Professor of Natural History at Edinburgh University in Scotland.

This position he held for about twelve years until he moved to Edinburgh as Regius Professor of natural history.

There he remained until 1870, when considerations of health induced him to resign his professorship and retire to Dorset, where he devoted himself to his favourite pastime of horticulture.

His most important work was upon the gymnoblast group of the hydrozoa, on which he published in 1871-1872, through the Ray Society, an exhaustive monograph, based largely on his own researches and illustrated with drawings of remarkable excellence from his own hand.

Biological science is also indebted to him for several convenient terms which have come into daily use, e.g. endoderm and ectoderm for the two cellular layers of the body-wall in Coelenterata.